Physics kinematics problem help?

Question

1. A physics student, exhausted after hours of study, plays a game to relieve her stress. She tries to slide an ice cube across the surface of her desk such that, when the cube slides off of the edge of the desk it lands in a bowl on the floor. The bowl is placed 1.3 m from a point on the floor directly below the edge of the desk, and the desk is 1.2 m above the floor. What velocity must she give the cube in order to have it land in the bowl?

 

2. If the ball was rolling at 12 m/s as it left the table and then subsequently landed on point "a", what is the value of "x"?

 

---------

           l

           l

           l

           -----------a

           ^___x___^

Answer 1

(1)

 

Vertically, it falls

 

y = (1/2)gt²

 

y = 1.2 m

 

Horizontally, it travels

 

x = vt

 

x = 1.3 m

 

Get t from the vertical drop, then plug it into x = vt to get v.

 

t = √(2y/g) = √[2(1.2)/9.8] s ≅ 0.4949 s

 

v = x/t = 1.3/0.4949 m/s = 2.6268 m/s

 

(2)

 

t is the same, since it depends only on the vertical drop.

 

x = vt = 12(0.4949) m ≅ 5.9388 m