How long will it take?

Question

A child rolls a ball up a hill at 4.24 m/s. If the ball experiences an acceleration of -1.32 m/s^2, how long will it take for the ball to have velocity of 2.23 m/s down the hill?

Answer 1

v_f=v_i+a*t

 

v_i=4.24 m/s

v_f=-2.23 m/s (why negative?)

a=-1.32 m/s²

 

Solve for t.

 

 

Answer 2

V = Vo + at

-2.23 = 4.24 - 1.32t

Solve for t,

t = 4.90 sec <==Answer