Interactive Quiz #1

This self-graded quiz consists of 10 questions. Answers are entered by clicking the option button corresponding to your selection. The quiz is graded by clicking the "Grade Quiz" button at the end of the quiz. Correct answers are found through hypertext links located at the end of the quiz.

1. Which of the following is a vector quantity?
    (A) the age of the Earth
    (B) the mass of a car
    (C) the Earth's pull on your body
    (D) the temperature of an iron bar
    (E) the number of students in Physics 111
2. Starting from rest, a particle which is confined to move along a straight line has an acceleration of 5.0 m/s2. Which statement accurately describes the motion of this particle?
    (A) The particle travels 5.0 m during each second.
    (B) The particle travels 5.0 m only during the first second.
    (C) The speed of the particle increases by 5.0 m/s during each second.
    (D) The acceleration of the particle increases by 5.0 m/s2 during each second.
    (E) The final speed of the particle will be proportional to the distance that the particle travels.
3. A car moves with a uniform speed of 30.0 m/s around a square racetrack. Its acceleration is
    (A) always zero.
    (B) constant and is directed towards the centre of the square.
    (C) zero, except at the corners of the square.
    (D) maximized along the sides of the square.
    (E) constant and is directed away from the centre of the square.
4. A box whose weight has a magnitude of W is sitting on a horizontal surface. The tension in a vertical rope attached to the top of the box has a magnitude T. If T < W, the magnitude of the normal force on the box is:
    (A) 0
    (B) W + T
    (C) W - T
    (D) T
    (E) W
5. An object of mass m is at rest on a flat horizontal surface. The coefficient of static friction between the object and the surface is µ. A horizontal force of magnitude F is applied to the object, but the object does not move. The magnitude of the static frictional force on the object is:
    (A) µmg
    (B) mg
    (C) µF
    (D) F
    (E) 0
6. Which force is responsible for keeping a car in a circular trajectory on a frictionless banked curve?
    (A) the vertical component of the car's weight
    (B) the vertical component of the normal force
    (C) the horizontal component of the car's weight
    (D) the horizontal component of the normal force
    (E) the component of the weight parallel to the road surface
7. The earth exerts the necessary centripetal force on an orbiting satellite to keep it moving in a circle at constant speed. Which statement best explains why the speed of the satellite does not change even though there is a net force exerted on it?
    (A) The satellite is in equilibrium.
    (B) The acceleration of the satellite is zero.
    (C) The satellite is in free fall.
    (D) The centripetal force is cancelled by the reaction force.
    (E) The centripetal force is always perpendicular to the velocity.
8. A block is dropped from a high tower and is falling freely under the influence of gravity. Ignoring air resistance, which statement is true concerning this situation?
    (A) There is zero work done by the force of gravity as the block falls.
    (B) The kinetic energy of the block increases by equal amounts over equal distances.
    (C) The kinetic energy of the block increases by equal amounts in equal times.
    (D) The potential energy of the block decreases by equal amounts in equal times.
    (E) The total energy of the block increases by equal amounts in equal distances.
9. A "T-ball" is hit by a baseball bat. The ball, with mass m, is stationary before it is hit. Just after being hit it has a speed v. If the average force of the bat on the ball during the collision is F, the time interval during which the bat is in contact with the ball was:
    (A) 2mv/F
    (B) 2mvF
    (C) F/mv
    (D) mv/F
    (E) Fv/m
10. Momentum will be conserved in a two-body collision only if
    (A) both bodies come to rest after the collision.
    (B) the collision is perfectly elastic.
    (C) the kinetic energy of the system is conserved.
    (D) the net external force acting on the two-body system is zero.
    (E) the internal forces of the two-body system are zero.
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Correct Answers

#1, #2, #3, #4, #5, #6, #7, #8, #9, #10
1. Which of the following is a vector quantity?
    (C) the Earth's pull on your body
Vectors are used to denote physical quantities that have direction as well as magnitude. See section 1.5 of text.
2. Starting from rest, a particle which is confined to move along a straight line has an acceleration of 5.0 m/s2. Which statement accurately describes the motion of this particle?
    (C) The speed of the particle increases by 5.0 m/s during each second.
Refer to the equations of kinematics for constant acceleration (Sections 2.3 and 2.4 of text).
3. A car moves with a uniform speed of 30.0 m/s around a square racetrack. Its acceleration is
    (C) zero, except at the corners of the square.
A change in velocity, including a change in direction, means there is an acceleration. See section 3.1 of text.
4. A box whose weight has a magnitude of W is sitting on a horizontal surface. The tension in a vertical rope attached to the top of the box has a magnitude T. If T < W, the magnitude of the normal force on the box is:
    (C) W - T
Since the box remains at rest (T < W), the sum of the forces in the vertical direction is 0. See section 4.8 of text.
5. An object of mass m is at rest on a flat horizontal surface. The coefficient of static friction between the object and the surface is µ. A horizontal force of magnitude F is applied to the object, but the object does not move. The magnitude of the static frictional force on the object is:
    (D) F
For no motion, the sum of the forces in the horizontal direction is 0. See section 4.2 of text.
6. Which force is responsible for keeping a car in a circular trajectory on a frictionless banked curve?
    (D) the horizontal component of the normal force
The centripetal acceleration is produced by the net horizontal force. See section 5.4 of text.
7. The earth exerts the necessary centripetal force on an orbiting satellite to keep it moving in a circle at constant speed. Which statement best explains why the speed of the satellite does not change event though there is a net force exerted on it?
    (E) The centripetal force is always perpendicular to the velocity.
For uniform circular motion, velocity is tangent to the orbit and centripetal force is directed radially inward. Therefore, there is no component of acceleration in the direction of the velocity so the speed remains constant. See sections 5.1, 5.2, and 5.3 of text.
8. A block is dropped from a high tower and is falling freely under the influence of gravity. Ignoring air resistance, which statement is true concerning this situation?
    (B) The kinetic energy of the block increases by equal amounts over equal distances.
In the absence of air resistance mechanical energy is conserved. Therefore since the gain in KE equals the loss in PE, and PE decreases proportionally with a decrease in height, KE increases proportionally with a decrease in height. See section 6.5 of text
9. A "T-ball" is hit by a baseball bat. The ball, with mass m, is stationary before it is hit. Just after being hit it has a speed v. If the average force of the bat on the ball during the collision is F, the time interval during which the bat is in contact with the ball was:
    (D) mv/F
Impulse-Momentum Theorem: the impulse acting on the ball equals the change in the ball's momentum. See section 7.1 of text
10. Momentum will be conserved in a two-body collision only if
    (D) the net external force acting on the two-body system is zero.
See section 7.2 of text.

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