Quiz

QUIZ

1. What is the SI unit for momentum?

a. Kilogram meters per second b. Kilogram meters per second squared c. Meters per kilogram per second squared d. Kilograms per second squared

Answer: b. There is no easy SI unit for momentum. Instead, it is listed in the known SI units for mass and velocity, which are kilogram meters per second. It depends on the mass as well as the velocity for something.

2. If the mass of something is 2 times the mass of something else, how does this change the momentum?

a. The momentum will be doubled. b. The momentum will be the square of 2 or will be quadrupled. c. The momentum will be the same. d. The momentum will be one-half the mass of the smaller object.

Answer: a. The momentum of something is directly proportional to its mass so it will double if the mass of an object doubles.

3. What are the SI units for impulse?

a. Newton-seconds b. Joules per second c. Newtons d. Kilograms per square meter per second

Answer: a. The SI unit will be in Newton-seconds, which means the amount of force applied over a period of time. Remember that impulse is the same as the change in momentum.

4. Which of the following is not considered a vector?

a. Impulse b. Momentum c. Speed d. Force

Answer: c. Each of these is a vector quantity, having both a direction and magnitude, except for speed which, by definition, does not have a direction but only has a magnitude.

5. What is not an example of a loss of kinetic energy that can occur in macroscopic systems that aren’t completely elastic when it comes to the collision of two objects?

a. Heat energy b. Friction c. Radiant energy d. Deformation

Answer: c. Heat, friction, sound, and deformation of objects can all detract from the true conservation of kinetic energy that is supposed to occur in elastic systems. Radiant energy is generally not a factor in these types of systems.

6. In general, in elastic conditions in one dimension, the equations revolve around the idea that what must be conserved?

a. Momentum and Internal kinetic energy b. Velocities and mass c. Total kinetic energy and velocities d. Acceleration and forces

Answer: a. In elastic conditions, momentum and internal kinetic energy are two things that must be conserved in an elastic collision between two objects in one dimension.

7. What is the kinetic energy of two identically-massed objects that approach each other with the same velocity v after they stick together in a perfectly inelastic way?

a. The kinetic energy will be the mass of each multiplied by the velocity squared. b. The kinetic energy will be zero. c. The kinetic energy will be in the opposite position at one-half mass times velocity squared. d. The kinetic energy cannot be calculated in this situation.

Answer: b. If this is a perfectly inelastic collision, the equally-massed objects will have a zero velocity after the collision, which means that the kinetic energy will be zero.

8. What type of collision between two objects represents a perfectly inelastic collision?

a. Two objects collide and stick together b. Two objects collide with zero friction c. Two objects collide and have springs attached that bounce off each other d. Two objects collide and neither of them are deformed

Answer: a. In a perfectly inelastic condition, the two objects collide and stick together. This will take away kinetic energy from a system to the maximal degree.

9. In the situation where an object strikes another object in the x-direction and both objects travel off in opposite directions, what is the velocity component in the direction of angle theta1 of the object that goes at that angle (theta1) from the y-axis?

a. Velocity after the collision multiplied by the sine of theta1. b. Velocity after the collision multiplied by the cosine of theta1. c. Velocity before the collision multiplied by the sine of theta1. d. Velocity before the collision multiplied by the cosine of theta1.

Answer: a. The velocity will not be the same as the velocity before the collision because of the collision. As the object heads of to an angle of theta1, its velocity in the y-axis will be the velocity after the collision multiplied by the sine of theta1.

10. What will be the proportionality between the total kinetic energy of an object after colliding with another object and its velocity after the collision?

a. The total kinetic energy will be proportion to the velocity squared multiplied by the cosine of theta squared where theta is the difference between the x-axis and the angle of its direction after the collision. b. The total kinetic energy will be proportional to the velocity squared multiplied by the sine of theta where theta is the difference between the xaxis and the angle of its direction after the collision. c. The total kinetic energy will be proportional to the velocity times the cosine of theta. d. The total kinetic energy will be proportional to the velocity squared.

Answer: d. The kinetic energy can be broken down into its xcomponent and its y-component; however, the total kinetic energy has both the x- and y-components so that it does not need the cosine of theta taken into account. In general, the kinetic energy is proportional to the velocity squared.