Question

A stone is released from the top of a towar reaches the ground after 4 s. Find the height of the towar calculate the velocity of the stone

Answer 1

Explanation:

Intial Speed of Stone(ul=0 m/s (As it was in rest when it was dropeed)

Time taken to Reach ground(t)=4s

Accerlation due to gravity (g)=10 m/s²

As We Know

Equation of motion

v=u+gt

v=0+gt

v=gt

v=10×4

v=40 m/s²

Final Velocity=40 m/s²

Now We get Final Velocity (v)=40 m/s²

Now Equation of Motion

v²=u²+2as

40²=0²+2×10×s (s=distance or displacement)

1600=20s

s=1600/20

s=80 m

Height of Tower=80 m

Answer 2

Initial speed = 0m/s

Time = 4 sec

Acceleration = 10 m/s²

Final velocity = ?

Now;

v = u + at

v = 0 + 10(4)

v = 40 m/s

Now

v² - u² = 2as

(40)² - (0)² = 2(10)s

1600 = 20s

20s = 1600

s = 80 m