Question

Solve the following examples.
a. An object takes 5 s to reach the grond
from a height of 5 m on a planet.
What is the value of g on the planet?
Ans: 0.4 m/s​

Answer 1

Given :

• Time taken (t) = 5 seconds
• Distance travelled (s) = 5 m

To Find :

• Value of acceleration due to gravity on the planet

Solution :

In this question we are given that an object is thrown vertically downwards from a height of 5 m and it takes 5 seconds to come to ground. And we have tk find the value of acceleration due to gravity on that planet.

For this we will use 2nd equation of motion :

$\bigstar \: \boxed{\boxed{\sf{s \: = \: ut \: + \: \dfrac{1}{2} at^2}}}$

Where,

• s is distance travelled
• a is acceleration due to gravity
• t is time taken
• u is initial velocity

We will take initial velocity as 0 m/s as the object is in state of rest before thrown downwards

⇒s = ut + ½ at²

⇒5 = 0(5) + ½ * a * (5)²

⇒5 = 0 + ½ * a * 25

⇒5 = 25a/2

⇒25a = 5 * 2

⇒25a = 10

⇒a = 10/25

⇒a = 0.4

$\therefore$ Acceleration due to gravity on the planet is 0.4 m/s²

Answer 2

Answer:

u=0

s=5m

t=5s

from second equation of motion,

S=ut+1/2at²

5=1/2g(5)²

g=10/25

0.4m/s²

hence the value of g on the planet is 0.4m/s²

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