# Civil Engineering - Surveying - Discussion

Discussion Forum : Surveying - Section 1 (Q.No. 49)
49.
Keeping the instrument height as 1.5 m, length of staff 4 m, the slope of the ground as 1 in 10, the sight on the down-slope, must be less than
30 m
25 m
20 m
15 m
Explanation:
No answer description is available. Let's discuss.
Discussion:
26 comments Page 1 of 3.

Sameer sopori said:   6 years ago
If we are levelling on the sloped surface then we need to keep staff near the instrument, otherwise, it will not be visible inside the instrument because of the slope (if the distance is more).
so here is the formula, UNDER WHICH DISTANCE WE MUST KEEP STAFF,
Sight= (Staff ht.- instrument ht.)/(1/10)
= (4 - 1.5) /0.1,
= 2.5/0.1,
= 25m.

If you will keep the staff more than 25m away from the instrument , IT WILL NOT BE VISIBLE INSIDE THE INSTRUMENT,
(5)

Roohullah jan said:   4 years ago
In a simple way we can say that;

Let consider the slope is downward which 1 in 10.

So at 10m, the staff reading becomes 1. 5+1=2. 5m (staff reading).

At 20 m distance reading becomes 3. 5m.

Similarly, at 25 m distance, the reading becomes 4m. Which is the full length of the staff?

Thanks.
(8)

Ashish tadewar said:   7 years ago
The Hi is 1.5m so when and staff 4m.
The reading will be 2.5m on staff on plane. The slope being 1 in 10.
2.5 * 10 = 25 on down slope.

BIKAS said:   5 years ago
Thanks @sameer.

But if rising slope then maximum distance measured only 15 meters am I right?

Slope = 1/10.
HI = 1.5m.

Height of staff = 4.0 m.
Sight = (4-1.5)/(1/10) = 25 m.

staff readings visible for staff height of 2.5m so distance is 2.5x10 = 25m.

S.Sarkar said:   8 years ago
Slope 1:10 that means down 1 m for each 10 m distance.

So, 2.5 x 10 = 25 m.

Avshesh said:   6 years ago
Staff visible= 4-1.5=2.5m,
Site=2.5/(1/10),
= 2.5x10,
= 25m.

Doss said:   8 years ago
The instrument height of 1.5m, staff height 4m so 4 - 1.5 = 2.5m.

Justin said:   8 years ago
Please tell me what is the different betwn downslope an upslope.