A ball thrown vertically upward reaches a maximum height of 50m above the level of projection. Calculate the time taken to reach the maximum heighth and speed of the throw

Physics Jamb, Waec, Neco Past Questions & Answers on Speed, Velocity and Acceleration

QUESTIONS 47. A ball thrown vertically upward reaches a maximum height of 50m above the level of projection. Calculate the : 

(i) time taken to reach the maximum height. 

(ii) speed of the throw. 

WAEC 2001 Ans: (i) 3.16s (ii)31.6m/s

SOLUTIONS 

Initial velocity u = 0m/s

h =50m

t = ?

v =?

1. Using s = ut + ½ gt²

50 = 0 x t + ½ x 10 x t²

50 = 0 + 5t²

50 = 5t²

t² = 50/5

t² = 10

t = √10

t = 3.16s Answer

ii) 

u = 0m/s

g = 10m/s²

t = 3.16s

Hence Using v = u + gt

V = 0 + 

10 x 3.16

V = 32.6m/a 

Or 

V² = u² +2gh

V² = 0² + 2(10)(50)

v² = 20 x 50 

v = √1000 

v = 31.62m/s