# Homework Help: Newton's laws problems

1. Aug 27, 2009

### cmculbert

1. The problem statement, all variables and given/known data
1) A freight train has a mass of 1.5 x 10^7 kg. If the locomotive can exert a constant pull of 7.5 x 10^5 N, how long does it take to increase the speed of the train from rest to 80 km/h?

2) A 5.0 g bullet leaves the muzzle of a rifle with a speed of 320 m/s. What force (assumed constant) is exerted on the bullet while it is traveling down the 0.82 m long barrel of the rifle?

3)A block of mass m = 2.0 kg is held in equilibrium on an incline of angle theta = 60 degrees by the horizontal force F. (a) Determine the value of F. (b) Determine the normal force exerted by the incline of on the block (ignore friction).

4)A shopper in a supermarket pushes a loaded cart with a horizontal force of 10 N. The cart has a mass of 30 kg. (a)How far will it move in 3.0 s, starting from rest? (ignore friction) (b)How far will it move in 3.0 s if the shopper places her 30 N child in the cart before she begins to push it?

5)Two objects of masses 10.0 kg and 5.00 kg are connected by a light string that passes over a frictionless pulley. The 5.00 kg object lies on a smooth incline of angle 40.0 degrees. Find the acceleration of the 5.00 kg object and the tension in the string.

2. Relevant equations
1) F=ma
2) w=mg
3) ???

3. The attempt at a solution

2. Aug 27, 2009

### mg0stisha

First, show your attempts at solving all of these.