Question

A body is dropped from the roof 10 m high. Calculate the time of fall and speed with which it hits the ground. Take g = 10 meter per second square.

Answer 1

s=10m
g=10m/s
u=0m/s [ Body Starts From Rest ]
v = ?

v^2 - u^2 = 2gs
v^2 - 0^2 = 2 x 10 x 10
v^2 = 200
v = Root Of 200 (√200)
v = 14.14 ( Approx. )
Speed = 14.14 m/s

v=u+gt
14.14=0+10 x t
14.14=10t
t=14.14/10
t= 1.414 seconds
Time = 1.414 seconds

Answer 2

Concept:

• One-dimensional motion
• Kinematic equations
• Free fall

Given:

• Height of fall S = 10 m
• The body has been dropped
• The initial velocity u = 0 m/s
• Acceleration due to gravity g = 10 m/s^2

Find:

• Time of fall t
• The final velocity of the body v

Solution:

We know the kinematic equation

s = ut + 1/2 at^2

s = 10 m, u = 0, a = g = 10 m/s^2

10 = 0 (t) + 1/2 (10)t^2

10 = 5 t^2

2 = t^2

t = √2 s

We also know the kinematic equation to calculate the final velocity

v = u + at
v = 0 + 10 (√2)

v = 10√2 m/s

The time of fall is √2s and the speed with which it hits the ground is 10√2 m/s.

#SPJ2