motion of an object

Question

A marble rolling with a speed 20cm/s rolls off the edge of a table that is 80cm high.how far horizontally from the table edge does the marble strike the floor

Answer 1

There are two motions when the marble exits the table

 

1. horizontal motion of 0.2m/s until the marble hits the floor and

2. vertical motion under gravity of 9.81 m/s^2

 

time taken to hit the floor under gravity, t = (2 * 0.8/9.81)^1/2 = 0.202 seconds (using h = 1/2*g*t^2)

 

displacement under constant velocity = velocity * time

 

horizontal displacement = horizontal velocity * time taken

 

horizontal distance = 0.2 m/s * 0.202 secs = 0.0404 m = 4cm