Question

A ball of mass 1.5kg is dropped from a tower 40m high 1. What is its speed when ihad covered 20m

Answer 1

Answer:

answer to the question is: 14√2m/s.

Explanation:

A ball which weight is 1.5 kg was left from a height of 40 m, what will be the speed when it will reach on 20 m?

A body when released downwards has initial speed(u)=0m/s.

Motion of body under gravity is weight independent.

Let the final speed when the ball hits the ground be v m/s.

We have to find the speed of the ball at a distance of 20m away from the ground. Let it denote by v2 m/s.

Let's denote A(=initial postion), B(=postion of body at 20m away from earth) and Z(=final position).

We have,

S=(v^2-u^2)/2g

Apply it from A-Z & B-Z as shown

A-Z:

40=(v^2–0^2)/2g…(1)

B-Z:

20=(v^2-v2^2)/2g…(2)

Solving (1) and (2),

v=(√2)*v2…(3)

Now we need to find v…

V^2=U^2+2*g*s

V=28m/s

Put v=28 in (3) to get

28=(√2)*v2

V2=14√2m/s.

Hence the answer to the question is: 14√2m/s.

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