A bullet fired vertically upward from a gun held 2.0m above the ground reaches its maximum height in 4.0s. Calculate its initial velocity

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

QUESTIONS 59. A bullet fired vertically upward from a gun held 2.0m above the ground reaches its maximum height in 4.0s. Calculate its initial velocity, (g = 10 m/s²) 

A. 10 m/s 

B. 8 m/s 

C. 40 m/s 

D. 20 m/s 

JAMB 2009(8) Ans: C 

Solutions 

U = 0

From the ground to where the gun was shot = 2.0m

Time from the ground = t = ?

...............................

From the point where the gun was shot to maximize height = h = ?

Time to maximum height is 4s

g = 10m/s

velocity at maximum height = v = 0

Initial velocity u = ?

Thus using v = u - gt

0 = u - gt

∴ u = at 

u = 10 x 4 

u = 40 mls