You are standing on a skateboard, initially at rest. a friend throws a very heavy ball towards you. you can either catch the ball or deflect the ball back towards your friend (such that it moves away from you with the same speed as it was originally thrown). what should you do in order to minimize your speed on the skateboard? choose one of the following three answers.
(a) your final speed on the skateboard will be the same regardless whether you catch the ball or deflect the ball.
(b) you should catch the hall.
(c) you should deflect the ball
since the boot-print was left there nearly 50 years ago, there has been very little wind and very little rain in that area, and plus, there have been very few people or other animals walking around in that spot to disturb it.
this is an example of newton's first law of motion:
an object at rest will remain at rest unless an unbalanced force acts upon it. similarly, a moving object will remain moving in a straight line at constant velocity unless an unbalanced force acts upon it.
the answer is c.
m = mass of the girl = 53.4 kg
m = mass of skateboard = 3.55 kg
v' = velocity of the combination of girl and skateboard before she jumps forward = 0
v = velocity of the girl forward = 1.32
v = velocity of the skateboard afterward = ?
using conservation of momentum
(m + m) v' = mv + m v
inserting the values
(53.4 + 3.55) (0) = (53.4) (1.32) + (3.55) v
v = - 19.86