Question

Q2.a)A stone lying at the edge of a road falls down into a river flowing below the
road. If the stone takes 2 sec to reach the river, then find:
i)the speed with which the stone strikes the water surface in the river.
ii)the average speed of the stone at the end of the fall .
iii) the height of the road from the river.b)A spring balance of the range 0-1 kg- wthas total 100 divisions on its scale. What is the least count of the spring
balance?

Answer 1

Answer:

Explanation:

)A stone lying at the edge of a road falls down into a river flowing below the

road. If the stone takes 2 sec to reach the river, then find:

i)the speed with which the stone strikes the water surface in the river.

ii)the average speed of the stone at the end of the fall .

iii) the height of the road from the river.b)A spring balance of the range 0-1 kg- wthas total 100 divisions on its scale. What is the least count of the spring

balance?

Answer 2

Given, time(t) = 2 seconds

As, the stone fell from rest,

Initial velocity(u)= 0 m/s

Gravity(g) = +9.8 m/s²(in direction of gravity,thus +)

Final velocity (v) = ?

Using

$v = u + gt \\ = > v = 0 + 9.8 \times 2 \\ = > v = 19.6 \frac{m}{s} \\ \\now \\ average \: speed = \frac{v + u}{2} = \frac{19.6 + 0}{2} = 9.8{ms}^{ - 1}$

(i) Thus, the speed with which the stone strikes the water surface in the river is 19.6 m/s.

(ii) Average speed is 9.8 m/s.

(iii) Using, s = ut + 1/2 gt²

s = 0 × 2 + 1/2 × 9.8× 2²

s = 9.8 × 2 = 19.6 m

Thus the distance(height) between the road and river is 19.6 m.

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