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Transcript
TRUE OR FALSE QUESTIONS
Circle the correct answer.
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19.
The rate at which velocity changes with time is called acceleration.
When a car rounds a comer at a constant speed, its acceleration is zero.
As a ball falls freely, the distance it falls each second is the same.
If you slide a hockey puck across a frictionless ice rink, there must be
a horizontal force on the puck to keep it in motion.
Excluding the force due to air pressure, there is only one force acting on a
book lying at rest on a tabletop.
If a bicycle and a parked car have a head-on collision, the force of impact is
greater on the bicycle.
A quantity that has both magnitude and direction is called a scalar.
When all forces acting on an object are balanced, the object is said to be in
equilibrium.
Momentum is defined as an object's mass times its velocity.
The reason a baseball player follows through when hitting the ball is to be in
contact with the ball for as long a time as possible.
The SI unit of work is called the joule.
The rate at which work is done is called energy.
When an object is balanced so that any displacement lowers its center of
gravity, the object is said to be in stable equilibrium.
There is a force on the earth that is directed toward the sun.
When the earth's shadow falls on the moon, a lunar eclipse occurs.
Ocean tides are caused by differences in the gravitational pull between the
Moon and the opposite sides of the earth.
A bug on a turning record will make more turns per minute if it walks toward
the center of the record.
Ladybugs on the inside of a spinning bicycle tire will experience a force that
feels like gravity to them.
In order to increase his or her rotational inertia, a tightrope walker can carry a
long stick.
MULTIPLE CHOICE QUESTIONS
Choose the best answer to each question and write the appropriate letter in the space provide6
26.
Suppose a car is moving in a straight line and steadily increases its speed.
It moves from 35 km/h to 40 km/h in the first second and from 40 km/h to
45 km/h in the next second. What is the car's acceleration?
a. 5 km/h/s
27.
c. 35 km/h/s
d. 40 km/h/s
A ball is thrown straight up. At the top of its path, its instantaneous speed is
a. 0 m/s.
28.
b. 10 km/h/s
b. about 5 m/s.
c. about 10 m/s.
d. about 20 m/s.
The law of inertia states that an object
a. at rest will remain at rest unless acted on by an outside force.
b. will continue moving at the same velocity unless an outside force acts on it.
c. will continue moving in a straight line unless an outside force acts on it.
d. All of the above
29.
How much force is needed to accelerate a 2-kg physics book from rest to a speed
of 6 m/s in 1 second?
a. 36 N
b. 12 N
c. 3 N
d. 0.33 N
30.
Friction is a force that always acts
a. in a direction opposite to the direction of an object's motion.
b. in the same direction as the object’s motion.
c. in a direction perpendicular to the object's motion.
31.
If a horse pulls on a wagon at rest, the wagon pulls back equally as much on the horse. Will
the wagon be set into motion?
a.
b.
c.
d.
32.
No, because the forces cancel each other.
Yes, because there is a net force acting on the wagon.
Yes, because there is a time delay between action and reaction.
Yes, because the horse's pull on the wagon is greater than the wagon's pull
on the horse
A cannonball is fired at some angle into the air. In the first second, it moves 10 meters
horizontally. Assuming it does not hit the ground and air resistance is small, how far will the
cannonball move horizontally in the next second?
a. More than 10 m
b. 10 m
c. Less than 10 m
d. There is not enough information to say.
33.
The reason padded dashboards are used in cars is that they
a. increase the force of impact in a collision.
b. increase the time of impact in a collision.
c. decrease the momentum of a collision.
d. decrease the impulse in a collision.
34.
F= ma is Newton’s ________ Law.
a. 1st
b. 2nd
c. 3rd
35.
If you lift one load up two stories, how much work do you do compared to lifting the same
load up only one story?
a. Four times as much
b. Twice as much
c. The same amount
d. One half as much
36.
How much power is required to do 200 J of work on an object in 2 seconds?
a. 400 W
b. 200 W
c. 100 W
d. 2W
37.
Kinetic energy is the energy an object has because of its
a. speed.
b. location.
c. size.
d. temperature.
38.
Compared to a car traveling at 50 km/s, how much farther will the same car
skid when it is traveling at 100 km/s?
a. Five times as far
b. Four times as far
c. Twice as far
d. The same distance
39.
If you try to touch your toes while standing flat against a wall, you will
probably fall over. This is because
a. your center of gravity is outside your support area.
b. your feet extend only a short distance.
c. your center of gravity extends beyond your feet.
d. All of the above
40.
The gravitational force between two masses
a. is always an attraction.
b. depends on how large the masses are.
c. depends inversely on the square of the distances between the masses.
d. All of the above
41.
You can tell if a gravitational force exists in a region of space if
a. you let go of a ball and it starts to move.
b. you disturb a pendulum and it starts swinging.
c. you can weigh yourself.
d. All of the above
42.
What remains constant for a satellite in an elliptical orbit?
a. Its speed
b. Its kinetic energy
c. Its potential energy
d. Its total energy
43.
Where does the pickup needle on a phonograph move the fastest across the record?
a. At the end of the record
b. At the beginning of the record
c. Everywhere, because it has the same speed everywhere on the record
44.
A car travels in a circle with constant speed. The net force on the car
a. is directed forward, in the direction of travel.
b. is directed toward the center of the curve.
c. is zero because the car is not accelerating.
d. None of the above
45.
The reason an ice skater turns faster when he pulls his hands in is that
a. angular momentum must be conserved.
b. there are no large unbalanced torques acting on him.
c. his rotational inertia changes.
d. All of the above
46.
Density is defined as
a. mass divided by volume.
b. mass times acceleration.
c. length divided by time.
d. length divided by volume.
ESSAY QUESTIONS
Answer the following questions on a separate piece of paper.
51.
A car accelerates from rest to 20 m/s second in 10 seconds. What is the car's
acceleration? Assuming that the car weighs 10 000 N, calculate the approximate
force acting on the car.
52.
Discuss how each of Newton's three laws of motion can be applied to a rubber
ball that is thrown inside a spaceship (in a zero-gravity environment) and bounces
off a wall. Where is momentum conserved?
53.
Define kinetic energy and gravitational potential energy. Discuss how each type of
energy changes into the other type as a pendulum swings back and forth. Indicate
where each type of energy is at a maximum and a minimum.