# Dynamics and Newton's Laws Help

1. Dec 6, 2007

### ArthurYan

I have been absent for the past few days and he expects the class to these question but I was absent while he was teaching this so I have NO idea with to do here.

1st question: A 745 kg sled, initially at rest on a frictionless horizontal surface, is subjected to a force of 22500 N (E) for 10.5 s. The sled is then allowed to coast for an additional 14.5s. While the sled is coasting, determine the force required in order to stop it within a 500.0 m distance.

2nd question: A 2.00 kg ball is released (from rest) into a tank filled with water. The buoyant forces acting on the ball total 11.6 N (up). The ball takes 3.70 s to reach the bottom of the tank. Determine the net force acting on the ball, the ball's acceleration, and the depth of the tank.

3rd question: Catchy parachutes to Earth at a constant velocity of 15.4 m/s (down). Cathy has a mass of 57.2 kg and her parachute has a mass of 22.8 kg. What is the net force acting on Cathy, and determine the force the parachute applies on Cathy.

Last question: A 1250.0 kg car pulls a 250.0 kg trailer by applying a 3500.0 N force backwards on the road. The resistant forces (friction, wind resistance, etc.) on the trailer are 200.0 and on the car are 700.0 N. Determine the acceleration of the car and trailer together, and determine the force the car exerts on the trailer.

Thanks for any help guys!