General Knowledge - Physics - Discussion

Discussion :: Physics - Section 1 (Q.No.2)

2. 

It is easier to roll a stone up a sloping road than to lift it vertical upwards because

[A]. work done in rolling is more than in lifting
[B]. work done in lifting the stone is equal to rolling it
[C]. work done in both is same but the rate of doing work is less in rolling
[D]. work done in rolling a stone is less than in lifting it

Answer: Option D

Explanation:

No answer description available for this question.

Harini said: (Sep 25, 2010)  
We need explanation please.

Vivek said: (Oct 12, 2010)  
Work done in rolling is less than lifting due to a extra work has been done in lifting due to gravity means against the gravity but in rolling on a inclined plane we get a work done by gravity in downward direction along the gravity.

Rajal said: (May 26, 2011)  
Work done in rolling case also include frictional coifficient of both the surface which reduce word done as compair to lifting.

Sruthi Raj said: (Jun 28, 2011)  
Like pulling is easier than pushing. Concept of friction.

Aroosa said: (Jul 7, 2011)  
Work done in rolling is less than lifting due to gravity.

Munish Karthik said: (Jul 11, 2011)  
Let's consider the comments of both vivek & rajal here.

1) when the body is supposed to lift upwards the gravity acts on it in the opposite direction (downwards).

2) when its rolled on an inclined surface the acts frictional force. But the work done is more in lifting upwards this is because for our consideration let it be mass=1kg,then weight=9.8N(w=m*g)

Then you need a force greater than the weight.But when its to move inclined instead of vertical less force is needed.

Let us consider its inclined at an angle of 1o degree then the body exerts a vertical force of (9.8*sin10)N and horizontal force of (9.8*cos10)N .

Now compare the case 1 & case 2 this shows that a body can be moved in (horizontal & inclined) easily than vertically.

[Note :to get the horizontal & vertical components refer parallelogram law]

Thank you a lot for reading my comment.

Sumit Khilwani said: (Sep 19, 2011)  
Force of gravity acting on stone in vertical position is greater than that of fprce acting during slidding position.

Ashish Chudhary Iitian said: (Oct 7, 2011)  
When we lift the block,we have to work against the gravitational force Mg but to roll the block up on the inclined plane it requires less work as Mg gets resolved.

Shiva said: (Oct 24, 2011)  
How is option B and D different?

Stephen said: (Feb 2, 2012)  
The answer is C. Work is force times distance. In this case, the force is the mass times gravity. Rolling up the hill reduces the magnitude of the force but increases the distance by the same magnitude, thus making the work the same; the rate is just decreased.

Anna said: (Feb 8, 2012)  
Same amount of work, just over a greater distance. It's gotta be C.

Mohib said: (Feb 11, 2012)  
The answer is definitly option D.

John said: (Feb 14, 2012)  
Actually we know that perpendicular is the smallest distance,

So the normal force at a shorter distance will be more effective in lifting than a vector's of normal force in rolling.

Subradeep said: (Feb 26, 2012)  
I think the work done in both cases is the same. Because the potential energy is the same in both cases, because we deal with gravity and gravity is a conservative force.

Snehasish said: (Feb 27, 2012)  
Stephen is not right bcoz work = force*displacement(not distance).So,option D is right.

Lazarous said: (Mar 1, 2012)  
D is the right answer that is true.

Aman Krishna said: (Apr 4, 2012)  
Here we have to consider the concept of inclined plane no doubt the amount of work done is same either we do it by rolling or pulling but one of the benefit is that gravitation force will be neglected.

More the slope less will be the effort.

Mridul said: (May 9, 2012)  
Work done in lifting is not more or less we feel it more due to the gravitational force acting on that object in same way we have to push it so no force required against gravity.

Npr Sharma said: (Sep 2, 2012)  
Whether you lift the stone or roll it up the slope ,stone gains potential energy equal to mgh .The stone gained this energy and by same amount you lost it ! Frictional force at the time of rolling up makes you to loose a little more of energy. You would have lost energy mgh when you lift it and mgh+ when you roll it up . Is it not better to lift then to roll it? Catch is here. There is mechanical advantage when you roll. Lever principle can be applied . Let the slope be 1/10. Rolling distance is 10 units whereas the lifting distance remains 1 unit . The effort is 1/10 now. You have a convenient comfort level ! In an ideal condition work done is same in both the cases. Rate of energy spending is less because you travel more distance. You spent less effort 1/10 and travelled 10 times more distance. Answer C is correct.

Mafel said: (Sep 5, 2012)  
It is easy to roll down because the work is done when we throw it in vertical direction.

Zoha Nasir said: (Oct 9, 2012)  
Since, the coefficient of rolling friction is less than the coefficient of sliding friction, the work done in rolling becomes less than lifting.

Curiosity said: (Oct 18, 2012)  
Since in a simple machine effort * effort arm = load * load arm.

In this case it is effort * hypotenuse of the rt angled triangle = load * perpendicular.
But perpendicular<hypotenuse.
Therefore effort<load.

Mandar said: (Oct 20, 2012)  
Work done is less if the object rolling and greater work is done if object lifting.

Mehak said: (Jan 8, 2013)  
Because in lifting a ball work done is against gravity and so large effort is to be applied than to roll it.

Debbrata Ghosh said: (Apr 1, 2013)  
I Know that When a Stone rolling, in that time friction Worked but its quantity not more than gravitational force. That caused option D is right.

Hassan Tukur said: (May 10, 2013)  
On my way becouse in the throwing the stone gravitational force oppose the motion but in rolling it on the ground there is no gravitational force opposing the motion.

Jennifer said: (Jun 11, 2013)  
This is practical. When lifting an object gravity takes more place than when rolling.

Veenu Mishra said: (Jun 24, 2013)  
This is related to concept of pulling and pushing. During pulling process friction force opposes the force applied hence work is increased in this case.

But in pushing (or rolling in this case) friction force helps and hence work is decreased. :).

Samsudeen Lastborn said: (Jul 27, 2013)  
(lifting and pulling) both will experience an opposition force. In lifting a force of gravity will be oppose while in that of pulling it experience d frictional force. i.e work done in lifting will be more than that of the pulling.

Jai said: (Aug 13, 2013)  
Force of gravity acting on stone in vertical position is greater than that of force acting.

Roktima said: (Aug 17, 2013)  
When we are lifting any object vertically, we just work against gravity (non-contact force). It is no matter whether the road is slope down or slope up. But in 2nd case, the concept of frictional force (contact force) is introduced. A roller touches its minimum parts on ground, so there less friction arises and it is easy to move. In case of moving downward we have to apply less energy than to moving upward just because of gravity.

Alia said: (Aug 24, 2013)  
When a stone is rolled up in an inclined plane than it is easier to apply force in upward direction because pulling is easier than pushing & one can use it's own weight while pushing as in case of pulley. So the answer will be D because firstly gravity is acting directly & vertically downward and secondly frictional force is introduced less in an inclined plane due to minimum contact with the road.

Aliyu Mukhtar Muhammad said: (Sep 8, 2013)  
The answer will be fall on the option if we look the question thoroughly.

Santosh Kumar said: (Nov 10, 2013)  
We know that a slope has a angle and a friction cause for non plane surface though gravity force F=mg where g is approxi constant so the force depend on the mass of object when we pull that object both our force and gravity force are occurred so it is easy to pull but hard to push.

Vrishali said: (Dec 26, 2013)  
Stone required less energy to rolling than lifting upward. It due to gravitational force of attraction acting on stone.

Victor Ify said: (Feb 9, 2014)  
Always remember that gravitational pull always tries to pull an object going upward downward so more work is done in lifting dan in rolling.

Raphael said: (Mar 24, 2014)  
The energy required to roll it down is less than the energy it required to lift it up.

Gurnam .Minhas said: (Mar 28, 2014)  
The answer should be "C". The total work done is how much distance the stone was moved from it's initial position. When you lift you the stone up and bring it down to the final destination the total distance is same and so the work done is same. The time it takes you to roll it is generally longer than lifting it. So the work done is same but the rate of work done is different. You use more "power" in lifting it but same "energy" as rolling it up. So more power is used for lifting it than rolling it but same work (energy) is used.

Muhammad Suhail said: (May 20, 2014)  
The correct answer is C. The work done in lifting is just the increase in potential energy, whereas the work done on the incline plane is the sum of the increase in potential energy and the work done against friction. Thus the work done along the inclined plane is in fact greater.

Sandeep Na said: (Jun 15, 2014)  
During rolling a stone potential energy stored in the body and kinetic friction between the stone increases and during lifting the body, the work done against the gravity according to newton second law. F=ma. During rolling the stone the force is towards the earth and also momentum increases.

Iqra said: (Jul 26, 2014)  
Answer is D during rolling on an inclined plane the sin (downward) component of gravitation force is zero while cos component is present at the time there is pushing force which is greater and opposite to this component of force and hence this component of force is neglected. And there is only force that is pushing force.

Hence work done is less in rolling.

Sourin said: (Aug 16, 2014)  
In rolling there's two components horizontal and vertical are acting and so the force or work required to roll on slope is divided into frictional resistance and partially to gravity. While in case of lifting have to overcome only the vertical component i.e, gravity so it becomes hard to fight gravity than to friction.

Naveen said: (Sep 18, 2014)  
In the case of rolling the body is motion so, small work is done.

Brighty said: (Sep 19, 2014)  
If we roll any object from slope or from any were the rolling of the body is less compared to lifting the object so the this the correct answer.

Node Pinches said: (Sep 20, 2014)  
Lifting a stone is against gravity while roling is supported by gravity.

Mohamad Iqbal Wani said: (Nov 9, 2014)  
D is 100 % correct answer.

Haleemah said: (Nov 11, 2014)  
Work done in lifting is greater than that of rolling.

Gary Bau said: (Nov 18, 2014)  
Answer C is correct.

In this context of rate of energy (power not work!) is greater and gravitational potential energy change (work) is the SAME.

To consider D is to revert to the thinking of Aristotle. Rather than Galileo and Newton.

Ryan said: (Jan 1, 2015)  
It may be a controversial issue since the question itself is not well asked in the first place. It all depends whether the two balls travel with the same displacement or not. Considering that they travel with the same displacement, more work is required to lift the ball vertically than to roll it along a slope.

Siddharth Awasthi said: (Feb 9, 2015)  
It is wrong.

Work done in both the cases is the same.

Because the work done is equal to the gain in potential energy and since they are being raised to the same height, the energy is same so the work in same. In case of rolling only the force required Is small but the work done is same.

Hishmakhan said: (Apr 18, 2015)  
May be because of force. Because on rolling as compared to lifting the required amount of force is less.

Neb said: (May 10, 2015)  
Work in vertical lifting = m*g*H.

Work on sloping rode = F*L = m*g*sin(slope)*L = m*g*H.

So work is the same, but the force, F, is less = m*g*sin(slope).

Daniel said: (Jul 11, 2015)  
C is the correct answer. Work done is the same but the rate at which the work done is less in the slope.

Ahmad said: (Nov 28, 2015)  
We all know that work done in lifting a stone vertically upward or rising a heavy object is never less than or equal to when pulled or pushed using a ramp or inclined plane why? Because when lifting it upward work is done against gravity while when using ramp.

Some of the force applied to push the stone overcome friction while the other force remaining is used to overcome the load but in the absence of friction the work done in raising the stone is equal to the work done using the inclined plane to pull the stone. Thanks for reading.

Htay Naing Oo said: (Dec 20, 2015)  
I think that if we lift this stone, we must effort a lot but if we roll it, we must effort a little. And so the work done is directly proportional to the effort.

Hassan Ibrahim said: (Jan 5, 2016)  
Definitely the correct option is D, if we thrown the stone vertically we lost more effort and the stone is directly return to the original position due to the gravity but when you thrown the stone incline there is no gravity and friction. So the work done in lifting is less than in rolling.

Gaurav Pandey 8867310148 said: (Feb 2, 2016)  
In case rollin their force component get resolved but in in case of lifting single force component act over body so according to work formula as we know that:

W = fdcoso.

Force component not resolved that's why value of cos increased. So over all work increased. against gravity f-is force d-is displacement.

Danquah Seth said: (Apr 10, 2016)  
Work done in rolling is less than lifting it up because the work done is force per distance of an object.
Here the force becomes directly proportional to the distance while in lifting the force becomes inversely proportional to distance because of potential energy possessed.

Yohan A said: (May 19, 2016)  
I think work done in both cases are the same, if and only if the inclined surface is frictionless because the conservative force does not depend on the path of the object.

Busayo said: (Jun 24, 2016)  
Much effort is been applied when lifting, less work is done when rolling.

Durgesh Tripathi said: (Jul 28, 2016)  
Since the perpendicular distance between stone and earth is less than slope. Hence force between stone and earth through the path of the slope is less than that between same through the perpendicular path by universal gravitational law. And the distance is more for slope and less for perpendicular for the same case. So, energy is constant ie, mgh. The coefficient of friction makes us easy to roll and increases power. I think C is correct.

Kenneth said: (Jul 29, 2016)  
The work is the same. Assuming initial velocity is equal to a final velocity in both situations (that is, they all are zero), then neither experienced a change in kinetic energy. I am assuming that they both are moved to the same height because this would be totally illogical and uninteresting, as well as unsolvable if they were not. Therefore work done by gravity in both is mg, they both are moved same distance vertically and gravity is opposing them the entire time, therefore, equal and opposite work had to be done. Now, considering friction, it's totally irrelevant. The stone is rolled, therefore friction is not doing work of any kind it is simply providing the torque necessary to cause the angular velocity to remain constant.

Deva said: (Aug 16, 2016)  
Pulling is easier than pushing.

Vintoni said: (Sep 26, 2016)  
In lifting the angle is 90, hence W = mg; w = m * sin90.
Therefore, at the angle for example, 10, w = m * sin10, which less than when the angle is ninety given there is no friction.

The Correct answer is D.

Wim said: (Oct 8, 2016)  
At the bottom the energy of the stone is X.

At the top X+m.g.h (m= stone mass, g= gravitational force m, h= height of the hill).

So for the stone, it doesn't matter how it is brought up. Somebody must "add" that potential energy to the stone.

What must a stone carrier overcome? By rolling, the friction of the stone and the hill and the constant lifting of (part) of the stone weight to make it roll. He must add the potential energy and overcome the friction.

By lifting and walking the carrier must add all the potential energy the stone gained at the top, But no friction is involved.

So how D is the right answer?

Hsu Pyae Sone said: (Oct 22, 2016)  
For me, it is difficult to say the difference between C and D. Which one is the truth? Someone explain it clearly to understand.

Zain said: (Nov 25, 2016)  
The work doesn't change in both cases, it's true the gravitational force will less in the second case but the distance will be greater so that the work is same.

Asiimwe Shabani said: (Nov 27, 2016)  
I agree with the given answer i.e D.

Jun said: (Dec 10, 2016)  
The questioned mentioned 'rolling'. Thus friction does not apply at all and as seen in many comments, work= force x distance, force is mg and is constant. Distance traveled is the same too as vertical height achieved is equal. (Horizontal distance of slope is not counted).

Jun said: (Dec 10, 2016)  
So work is same. Answer is supposed to be freaking 'c'.

Basic physics c'mon guys.

Jun said: (Dec 10, 2016)  
(Zain said: (Nov 25, 2016).

The work doesn't change in both cases, it's true the gravitational force will less in the second case but the distance will be greater so that the work is same. ).

Fgs, gravitational force is constant and only vertical distance is relevant so it's the same too.

Usman Abdullahi Karwai said: (Dec 20, 2016)  
Answer is D, because the ball rolling is against the gravity that's why it's less.

Sharma said: (Jan 24, 2017)  
The exact answar should be D. Because in vertically upward we have to force against mg. But in rolling the opposite force is mgsin. And we are putting force against mgsin. mgsin<mg. So rolling is less than vertically.

Pavankumar said: (Mar 8, 2017)  
Answer is D. Because for lifting objects it has more force of gravity and for rolling objects, it is less, friction of rolling is less. So it is easy to roll the stone.

Chris said: (Apr 18, 2017)  
The work done in rolling is mg sin(theta) multiply by the length of the slope (assuming no friction) where theta is less than 90°. But work done in lifting vertically should be mgh where h is the height of the slope and angle to horizontal is 90. since sine of any angle less than 90° is always less than one, working in rolling is always less than the work done in lifting.

Varshitha said: (Dec 6, 2017)  
Since we are rolling in an inclined plane frictional force is less an due to gravitational force lesser work is required, we lift the object it's against gravitational force w=mg is acting so more work is required. And the answer is D.

Chua said: (Jan 19, 2018)  
The answer should be C. Work done is the same (neglecting frictional force). Pushing force is mgsin but pushing distance is mgh/sin. So work done work done is still mgh in both cases.

Emmy said: (May 13, 2018)  
I strongly agree with the answer, because when you roll less effort is applied than when lifting. Thanks.

Sam said: (Jun 21, 2018)  
@ALL.

We conservation of linear momentum = angular momentum.

Abhishek said: (Jun 26, 2018)  
The answer is option D because rolling is easier than lifting because while lifting an object you opposing gravity, the more the mass of an object heavier the object, but in case of rolling the object is moving but without any opposition of strong as much as gravity but there will opposing force which is friction but It will not affect as much as gravity.

James said: (Apr 25, 2019)  
@All.

Here all are making a mistake with using "Force" and "Work". The work is the same in this question. Since you need less Force to push/pull the object on a slope (without friction applied) than vertically. But the distance is more on the Slope than vertically. Thus W = F x s -> W1 = W2.

Ramana said: (Apr 27, 2019)  
C is the correct answer.

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