Physics Help?

Question

Robert places his bowling ball on a table. It rolls off a table 1m high with a speed of 4m/s. How far from the base of the table does it land?

Answer 1

analyze the problem as 2 one-dimensional problems.

In the vertical direction the initial velocity is zero and the ball falls under gravitational acceleration

h = 0.5gt²  where t is the time and h is the height

1 = 0.5 (9.8) t²

t = sqrt(1/4.9) = 0.45 s

In this amount of time the bowling ball horizontal velocity will carry it a distance of 

= vt = 4 * 0.45 = 1.81 m

 

Answer 2

The time it takes the ball to fall is:

 

     t = (2h/g)^1/2

 

where h = 1 m and g = 9.8 m/s².  Hence:

 

     t = (2*1/9.8)^1/2 = 0.45 s

 

The distance the ball travels horizontally is:

 

     d = v*t = (4 m/s)*(0.45 s) = 1.8 m