Question

A particle is thrown in upward direction with initial velocity of 60 m/s. Find average speed and average velocity after 10 seconds. [g = 10 ms^–2] 

(A) 26ms^–1, 16ms^–1 

(B) 26ms^–1, 10ms^–1 

(C) 20ms^–1, 10ms^–1 

(D) 15ms^–1, 25ms^–1

Answer 1

Correct option: (B) 26ms^–1, 10ms^–1

Explanation:

initial velocity = 60 m/s 

acceleration = 10 m/s also v = 60 + (– 10) (10) = 40 m/s 

particle is thrown in upward direction. Its velocity will decrease till it reaches top and increases while coming down.

average speed in upward dirⁿ = {(60 + 50 + 40 + 30 + 20 + 10 + 0) / 7} = 30 m/s 

average speed in downward dirⁿ = {(0 + 10 + 20 + 30 + 40) / 5} = 20 m/s 

average speed = [{(30) × (6) + (20) × (4)} / {10}] = [{260} / {10}] = 26 m/s 

average velocity = [{60 + (– 40)} / {2}] 

= 10 m/s ----- taking downward velocity negative.