Studied by 0 peopleIf no external forces act on a moving object, it will
A) continue moving at the same speed.
B) move slower and slower until it finally stops.
C) come to an abrupt halt.
D) none of the above
A
A hockey puck sliding across the ice finally comes to rest because
A) it seeks its proper and natural state.
B) of friction.
C) that's just the way it is
B
The amount of force needed to sustain motion of a rock in outer space is
A) a force equal to its weight.
B) a force less than its weight if friction is absent.
C) none of these
C
When no forces act on moving objects their paths are normally
A) straight lines.
B) circles.
C) ellipses.
D) all of the above
A
If gravity between the Sun and Earth suddenly vanished, Earth would continue moving in
A) a curved path.
B) an outward spiral path.
C) an inward spiral path.
D) a straight-line path
D
Which concept is being illustrated when a tablecloth is quickly yanked beneath dishes resting on a table?
A) equilibrium
B) friction
C) support force
D) inertia
D
When a rocket ship gaining speed in outer space runs out of fuel, it
A) gains speed for a short time, then slows down to a constant velocity.
B) gains speed for a short time, slows down, and eventually stops.
C) no longer gains speed
C
The net force on any object in equilibrium is
A) zero.
B) equal to its weight.
C) less than its weight.
D) non-zero when motion is involved
A
The equilibrium rule, ΣF = 0, applies to
A) objects or systems at rest.
B) objects or systems in uniform motion in a straight line.
C) both of these
D) neither of these
C
The support force on a 10-N book at rest on a table is A) slightly less than 10 N.
B) 10 N.
C) slightly greater than 10 N.
D) dependent on the position of the book
B
Weigh yourself on a weighing scale and the scale shows your normal weight. If you carefully stand on tiptoes, the scale reading will be
A) slightly more.
B) slightly less.
C) about half as much.
D) no different
D
A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the same direction has a speed of A)0m/s.
B)3m/s.
C)4m/s.
D)6m/s.
D
A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the opposite direction has a speed of
A) 0 m/s.
B) 3 m/s.
C) 4 m/s.
D) 6 m/s.
A
The speedometer of an automobile reads
A) average speed.
B) instantaneous speed.
C) accelerated speed.
B
A vehicle undergoes acceleration when it
A) gains speed.
B) loses speed.
C) changes its direction.
D) all of the above
D
While a car travels around a circular track at a constant speed, its
A) acceleration is zero.
B) velocity is zero. C) inertia is zero.
D) none of the above
D
A freely-falling watermelon falls with constant
A) velocity.
B) speed.
C) acceleration.
D) distances each successive second
C
If a freely falling object were equipped with a speedometer, its speed reading would increase each second by about
A) 5 m/s.
B) 10 m/s.
C) 15 m/s.
D) a variable amount.
E) depends on its initial speed
B
If an apple experiences a constant net force, it will have a constant
A) velocity.
B) speed.
C) acceleration.
D) position.
C
If you double the net force on an object, you'll double its
A) acceleration.
B) speed.
C) velocity.
D) all the above
A
A mobile phone is pulled northward by a force of 10 N and at the same time pulled southward by another force of 15 N. The resultant force on the phone is
A) 0 N.
B) 5 N.
C) 25 N.
D) 150 N
B
Compared to the mass of an apple on Earth, the mass of the apple on the Moon is
A) one sixth as much.
B) the same.
C) six times as much.
D) zero.
B
At equilibrium on a bathroom scale, the downward pull of gravity on you is balanced by
A) your weight.
B) an upward support force.
C) your mass.
B
A constant net force on a rail-road car produces constant
A) velocity.
B) acceleration.
C) both of these
D) neither of these
B
If an object's mass is decreasing while a constant force is applied to the object, the acceleration
A) decreases.
B) increases.
C) remains the same
B
A car by itself is capable of a certain maximum acceleration. When it tows a car of the same mass, its maximum acceleration is
A) one half.
B) one third.
C) one fourth.
D) the same.
E) none of these
A
You cannot exert a force on a wall
A) if the wall resists.
B) unless you put your mind to it.
C) unless the wall simultaneously exerts the same amount of force on
C
For every action force, there must be a reaction force that
A) acts in the same direction.
B) is slightly smaller in magnitude than the action force.
C) is slightly larger in magnitude than the action force. D) is equal in magnitude
D
When a ball falls downward, it may have a net force
A) equal to its weight.
B) of zero.
C) equal to its weight minus air drag.
D) any of the above
D
The attraction between Earth and Sydney is equal to her weight. The reaction to Earth's pull on Sydney is
A) Sydney pushing against Earth's surface.
B) the support of Earth's surface on Sydney.
C) Sydney's pull on Earth.
D) none of the above
C
The force that propels a cannonball when fired from a cannon is
A) huge compared to the recoil force on the cannon. B) equal and opposite to the force the ball exerts on the cannon.
C) in some cases, equal and opposite to the force the ball exerts on the cannon
B
A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is
A) zero.
B) twice.
C) four times as much.
D) unchanged.
B
The speed ofa 4-kg ball with a momentum of12kgm/s is
A)3m/s.
B)4m/s.
C) 12 m/s.
D) 48 m/s.
A
Padded dashboards in cars are safer in an accident than non-padded ones because passengers hitting the dashboard encounter
A) lengthened time of contact.
B) shorter time of contact.
C) decreased impulse.
D) increased momentum.
A
When you jump from an elevated position you usually bend your knees upon reaching the ground, which makes the time of the contact about 10 times that of a stiff-legged landing. In this way the average force your body experiences is
A) less than 1/10 as great.
B) more than 1/10 as great.
C) about 1/10 as great.
D) about 10 times as great
C
A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared with the force that stops the car, the force needed to stop the truck is
A) greater.
B) smaller.
C) the same.
A
If a monkey floating in outer space throws his hat away, the hat and the monkey will both
A) move away from each other, but at different speeds. B) move away from each other at the same speed.
C) move a short distance and then slow down.
D) move a short distance and then go faster.
A
The work you do when pushing a shopping cart a given distance while applying twice as much force is
A) half as much.
B) twice as much.
C) four times as much.
D) the same amount
B
Relative to an initial height, an object raised twice as high has a gravitational potential energy
A) half as much
B) twice as much.
C) four times as much.
D) need more information
B
An object that has kinetic energy must be
A) moving.
B) falling.
C) at an elevated position.
D) at rest.
E) none of the above
A
If a Ping-Pong ball and a golf ball both move in the same direction with the same amount of kinetic energy, the speed of the Ping-Pong ball must be
A) less than the golf ball.
B) more than the golf ball.
C) both the same
D) need more information
B
A ball rolling down an incline has its maximum potential energy at
A) the top.
B) a quarter of the way down.
C) halfway down.
D) the bottom.
A
A block of ice sliding down an incline has half its maximum kinetic energy
A) at the top.
B) at the bottom.
C) halfway down.
D) need more information
C
Horses with the greatest linear speed on a merry-go-round are located
A) near the center.
B) near the outside.
C) anywhere, because they all move at the same speed
B
Horses with the greatest rotational speed on a merry-go-round are located
A) near the center.
B) near the outside.
C) anywhere, because they all move at the same speed
C
The net force exerted on a car traveling in a circular path at constant speed is
A)directed forward, in the direction of travel.
B) directed toward the center of the curve.
C) zero because the car is not accelerating.
D) none of the above
B
The rotational inertia of your leg is greater when your leg is
A) straight.
B) bent.
C) same either way
A
A ring and a disk both at rest roll down a hill together. Which rolls slower?
A) ring
B) disk
C) depends on the masses
D) both roll at the same speed
A
If you place a pipe over the end of a wrench when trying to rotate a stubborn bolt, effectively making the wrench handle twice as long, you'll multiply the torque by
A) two.
B) four.
C) eight.
A
The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is
A) relatively low for such a tall building.
B) stabilized by its structure.
C) displaced from its center.
D) above a place of support.
E) in the same place as its center of mass.
D
When a twirling ice skater brings her arms inward, her rotational speed
A) decreases.
B) remains the same.
C) increases.
C
When a twirling ice skater brings her arms inward, her rotational inertia
A) decreases.
B) remains the same.
C) increases.
A
According to Newton, when the distance between two interacting objects doubles, the gravitational force is A) half. B) one-quarter.
C) the same.
D) twice as much.
E) four times as much
B
If Earth's radius somehow increased with no change in mass, your weight would
A) increase also.
B) decrease.
C) stay the same
B
Two objects move toward each other due to gravity. As the objects get closer and closer, the force between them
A) increases.
B) decreases.
C) remains constant.
A
Inside a freely-falling runaway elevator, your
A) acceleration is zero.
B) weight is zero.
C) gravitational interaction with Earth is zero.
D) all of the above
If the Sun were twice as massive
A) its pull on Earth would double.
B) the pull of Earth on the Sun would double.
C) both of these
D) neither of these
C
As soon as a bowling ball rolls off the edge of a table its horizontal component of velocity
A) decreases.
B) remains constant.
C) increases
B
A ball rolls off the edge of a table at the same time another ball drops vertically from the same table. The ball to hit the floor first is the
A) rolling ball.
B) dropped ball.
C) both hit at the same time
C
The Moon does not crash into Earth because
A) Earth's gravitational field is relatively weak at the Moon.
B) the gravitational pull of other planets keeps the Moon up.
C) Moon has a sufficient tangential speed. D) Moon has less mass than Earth.
E) none of the above
C
Project a cannonball from atop Newton's hypothetical mountain at 8 km/s and it orbits Earth. Project it at 9 km/s and the shape of the orbit is
A) a somewhat larger circle.
B) a wide parabola.
C) an ellipse.
C
Newton’s First Law
Law of Inertia) an object in motion tends to stay in motion & an object at rest stays at rest unless acted upon by an non-zero outside force.
Inertia
The tendency of an object to resist a change in motion
Force
A push or a pull
Net Force
The sum of all forces acting on an object
Mechanical Equilibrium
Experiences a net force of zero
Equillibrium Rule- Sum of forces = 0
No change, static or moving at a constant speed in straight line.
Speed
distance/time
Instantaneous Speed
The rate at which an object is moving at a given moment in time
Average Speed
the total distance traveled by the object in a particular time interval.
Velocity
acceleration x time
Vectors- 2 things
It has magnitude and direction, an arrow that represents the vector quantity
Acceleration
The rate at which velocity itself changes. (applies to increases and decreases in velocity)
Free Fall
The only force being applied to the mass object is gravity
Unballanced Force
Unbalanced forces acting on an object cause the object to accelerate.
Friction
when surfaces slide or tend to slide over one another. (always opposite to motion)
Sliding friction is less that the friction that builds up before the sliding takes place.
Static friction is greater than sliding friction
Mass
the amount of matter in an object
Weight
the force of gravity on an object's mass
Newton’s Second Law
The acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object.
Newton-Unit
One newton is equal to 1 kilogram meter per second squared.
Terminal Velocity
the maximum velocity (speed) attainable by an object as it falls through a fluid
Newton’s Thirst Law
For every action there is an equal and opposite reaction.
Vector Quantity
It has magnitude and direction
Scalar Quantity
a quantity that can be described by magnitude only and has no direction
Resultant
Sum of One or two vectors
Components
A vector resolved into two component vectors that are perpendicular to each other.
Note
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