Physics 1101 In-Class Problems: Newton's Laws

1. In the diagrams below, a ball is on a flat horizontal surface. The initial velocity and constant external forces acting on the ball are indicated. Describe qualitatively how motion the motion of the ball will change.
   

2. The 80.0 kg male partner of a figure skating duo pushes his 60.0 kg female partner with a force of 70.0 N. Find the acceleration of both partners.

3. What is the normal force on the object of mass m₁ shown in the diagram? What is the acceleration of the object? In the diagram F₁ = 25 N, F₂ = 15 N, and m₁ = 20 kg.
   
   

4. The apparent eight of a person in an elevator is 7/8^th of his actual weight. What is the acceleration (including the direction) of the elevator?
   

5. A person is standing on a weigh scale in an elevator. When the elevator is accelerating upward with constant acceleration a, the scale reads 867.0 N. When the elevator is accelerating downwards with the same constant acceleration a, the scale reads 604.5 N. Determine the magnitude of the acceleration a, the weight of the person, and the mass of the person.
   

6. A car is traveling over the crest of a small semi-circular hill of radius R = 750 m. How fast would it have to be traveling for it to leave the ground?

7. In the diagram below, block A weighs 100N. The coefficient of static friction between the block and the surface on which it rests is 0.40 and the kinetic coefficient is 0,25. Find the maximum weight w for which the system will remain in equilibrium.
   
   

8. A force F pushes on a 25-kg box as shown in the figure below. The coefficient of static friction between box and incline is μ_s = 0.20 . Find the range of values for which the block remains stationary.
   

9. What must be the acceleration of the cart pictured below in order that block A does not fall? The coefficient of friction between the block and the cart is μ_s.
   

10. Three blocks with masses 6 kg, 9 kg, and 10 kg are connected as shown below. The coefficient of kinetic friction between the 10-kg block and the table is 0.2 . Find the acceleration of the system. Find the tension in each cord.
    
    

11. A 10-kg block is hanging from a spring with spring constant K = 1000 N/m. The spring is attached to the ceiling of an elevator. The elevator is currently moving upwards at 10 m/s and slowing down at 1.0 m/s². How much is the spring stretched?

Questions? mike.coombes@kwantlen.ca