General Knowledge - Physics - Discussion

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.

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.

Pulling is easier than pushing.

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.

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?

For me, it is difficult to say the difference between C and D. Which one is the truth? Someone explain it clearly to understand.

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.

I agree with the given answer i.e D.

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).

So work is same. Answer is supposed to be freaking 'c'.

Basic physics c'mon guys.