SPH4U - UNIT TEST - Energy and Momentum
Instructor: Mr Shaw / Ms Binoy Date: June 20, 2012
Introduction
This unit focuses on the concepts of work, energy, momentum, and the laws of conservation of energy and conservation of momentum, in one and two dimensions. These terms have been defined, and questions related to knowledge and understanding are in section A. Questions demonstrating communications skills including short answer, diagrams, and correct terminology are in section B. Section C involves integrating knowledge and understanding to answer deeper questions which require connection between the concepts introduced.
Test Instructions
The test will take 1 hour to complete. You do not need a calculator, only a pen or pencil, eraser. Blank worksheets will be available, but these must be stapled to the test paper. Each section A, B, and C are equally weighted for a total of 18 marks, allocate your time appropriately to answer each section. In section C ensure you provide proofs to support your answers. If you have any questions raise your hand, and the test monitor will come. Good luck!
A. Multiple Choice – Knowledge and Understanding (1 mark each)
Identify the letter of the choice that best completes the statement or answers the question.
____ 1. Which of the following is not a unit of energy?
a. J
b. e.
c. N×m
d. W×s
e. kg*m/s2
ANSWER: E
____ 2. In the picture of a roller coaster track shown above, the point where the roller coaster car would be travelling the fastest, under negligible friction is
a. A
b. B
c. C
d. D
e. E
ANSWER: C
____ 3. A car with a mass of 1800 kg slows from 42 km/h [E] to 28 km/h [E]. The impulse from the brakes is
a. 2.5 ´ 104 N×s [E]
b. 2.5 ´ 104 N×s [W]
c. 2.1 ´104 N×s [E]
d. 2.1 ´ 104 N×s [W]
e. 7.0 ´ 103 N×s [W]
ANSWER: E
____ 4. Two objects of equal mass with the speeds indicated by the vectors below, collide and stick together.
Which vector below best represents the velocity of the combined objects after the collision?
a. A
b. B
c. C
d. D
e. E
ANSWER: D
____ 5. Looking at the diagram below, in which part of the orbit is the planet moving the fastest?
a. A
b. B
c. C
d. D
e. none of the above
ANSWER: A
____ 6. If an orbiting satellite has a total energy of –1.4 ´ 1012 J, then the binding energy is
a. –1.4 ´ 1012 J
b. +1.4 ´ 1012 J
c. –2.8 ´ 1012 J
d. –7.0 ´ 1011 J
e. not enough information
ANSWER:
B. Short Answer - Communications
1. Explain how is natural gravitational potential energy used to create electric energy? (2 marks)
ANSWER:
Hydroelectric generating stations convert the gravitational energy of water as it falls down rivers and converts it into electrical energy.
2. Many vehicles produced today are designed with “crumple zones.” How does this feature protect the occupants of the car? (2 marks)
ANSWER:
The crumple zone is designed to maximize the time (and the distance) over which the force to stop the car is exerted. This reduces the size of the force that acts on the passengers, minimizing the injury.
3. Using Newton’s Cradle consider the collision between two balls. One ball is at rest in space and the other ball is moving towards it. When the two balls collide, ball one exerts a force on ball two. Since this is really just one interaction, the force two exerts on ball one has the same magnitude. This means that the change in momentum of the two balls are opposite of each other. Draw the forces and momentum vectors at the instance of collision. (2 marks)
ANSWER :
C. Problems – Thinking and Inquiry
Provide proofs for your answers, annotate the diagram as required.
A steel ball of mass 1.0 kg rolls down a 1.0 m high ramp and, at the bottom collides with a 2.5 kg ball, which then proceeds up the adjacent ramp to a maximum height of 0.2 m. If the motion and collision are frictionless,
i) What is the velocity of each ball immediately after the collision? (2 marks)
ii) What type of collision occurred? (correlate Energy and momentumtransfer) (4 marks)
ANSWERS:
6/6