Force and Free Body Diagram

ASSIGNMENT 2

DUE DATE: 4 DECEMBER 2012 (Submit into Mr. Ng Poh Kiat’s pigeon box)

Instructions: This is an individual assignment. Answer both Section A and Section B. Your answers MUST be in written form. Marks will be deducted if printed copies, photocopies or electronic formats are submitted. Please submit only the answer sheet with your name and student ID on it. Marks will be deducted for late submission.

Section A (6 marks)

1. What is the definition of mass? A. How much something weighs. B. How hard something pushes on the ground. C. Resistance of an object to acceleration if it is otherwise able to freely move. D. None of the above.

2. Inertia is ________. A. A property of matter B. A type of force C. The speed of an object D. Any of the above

3. P and Q are two objects with masses 100 kg and 75 kg respectively, then ________. A. Both will have the same inertia B. Q will have more inertia C. P will have more inertia D. Both will have less inertia

4. Newton's second law of motion states that an unbalanced force that acts upon an object causes it to: A. Accelerate B. Not accelerate (keep the same velocity) C. Have a velocity D. Have a displacement

5. If two boxes are pushed with the same amount of total force, and one weighs 1kg and the other weighs 100kg, which one will accelerate faster? A. 1 kg box. B. 100 kg box. C. They will accelerate at the same rate. D. Neither will accelerate.

6. What is the force acting on an object of mass 10 kg moving with a uniform velocity of 10 m/s? A. 100 N B. 10 N C. 0 D. 1 N

Section B

1. A 3kg box is being pulled with a force of 12 N (See Figure 1). The position-time graph of the box is given in Figure 2. a. Sketch a free body diagram of the forces acting on the box. (2 marks) b. Determine the coefficient of friction between box and surface. (3 marks) Position
Time

F = 12 N

m = 3 kg

Figure 1 Figure 2 2. An applied force of 50 N is used to accelerate an object to the right across a frictional surface. The object encounters 10 N of friction. Using the free body diagram in Figure 3 and by neglecting air resistance, determine the: a. Normal force of the object. (1 mark) b. The net force of the object. (1 mark) c. The mass of the object. (1 mark) d. The acceleration of the object. (1 mark)

Figure 3