Question

An object was thrown upwards at a speed of 14 ms-1 and flew 10 m high. Calculate the time taken by the object to reach the highest point.
1. 1.63 s
2. 1.43 s
3. 1.53 s
4. 1.33 s

Answer 1

Correct Answer - Option 2 : 1.43 s

The correct answer is 1.43 s.

• In order to calculate the time taken by the object to the highest point, we have to calculate the initial velocity of the object.
• To calculate the initial velocity, we have to use the formula v² - u² = 2gs.
  • Here, v is the final velocity and u is the initial velocity with which the object was thrown up.
• To calculate the time, we have to use the formula v = u + gt.
• Here, t = v - u / g.

Solution:

Initial Speed (u) = 14 m/s 

Final speed (v) = 0 m/s

Acceleration due to gravity (g) = - 9.8 m/s²

we know,

⇒ v = u + gt

⇒ 0 = (14) + (- 9.8) × t

⇒ 14 = 9.8t

⇒ t = 1.42 s

• G is gravity constant.
• The value of G is 6.67430 ( 15 ) x 10^-11.
• It is also known as the Newtonian constant of gravitation.