Physics chapter 1-10
An object moves around a circle. If the radius is doubled keeping the speed the same then the magnitude of the centripetal force must be
Half as great
The SI standard of time is based on
None of these
Which of the following is a vector quantity
None of these
Acceleration is always in the direction
Of the net force
An object is shot from the back of a railroad flatcar moving at 40 km /h on a straight horizontal road. The launcher is aimed upward, perpendicular to the bed of the flatcar. The object falls
On the flatcar
Two objects are traveling around different circular orbits with constant speed. They both have the same acceleration but object A is traveling twice as fast as object B. The orbit radius for object A is ______ the orbit radius for object B.
One half
A man sits in the back of a canoe in Stillwater. He then moves to the front of the canoe and sits there. Afterward the canoe
Is rearward of its original position and not moving
A projectile in flight explodes into several fragments. The total momentum of the fragments immediately after this explosion
Is the same as the momentum of the projectile immediately before the explosion
A ball is thrown upward into the air with a speed that is greater than terminal speed. On the way up it slows down and , after its speed equals the terminal speed but before it gets to the top of its trajectory
It continues to slow down
A body at rest in a system is capable of doing work if
It is free to move in such a way as to decrease the potential energy of the system
The center of mass of a system of particles remains at the same place if
It is initially at rest and the external forces sum to zero
There is no SI base unit for area because
Area can be expressed in terms of square meters
The term "mass" refers to the same physical concept as
Inertia
The mass of a body
Is independent of the free fall acceleration
Only if a force on a particle is conservative
Is it's work zero when the particle moves exactly once around any closed path
Two objects p and q have the same momentum. Q has more kinetic energy than p if it
Is moving faster than p
The work done by gravity during the descent of a projectile
Is positive
Two objects, one having three times the mass of the other, are dropped from the same height in a vacuum. At the end of the fall, their velocities are equal because
None of the above
Whenever an object strikes a stationary object of equal mass
None of the above
Which one of the following is true
None of the above
Which of the following statements is true for the system consisting of the two masses
None of the above are true
A particle moves on the x axis. When its acceleration is positive and increasing
None of the above must be true
A watt per hour is a unit of
None of these
A block slides across a rough horizontal table top , the work done by friction changes
Only the kinetic and internal energies
We say that the displacement of a particle is a vector quantity. Our best justification for this assertion is
Operating with displacements according to the rules for manipulating vectors leads to results in agreement with experiments
A stone thrown from the top of a tall building follows a path that is
Parabolic
A particle moves at constant speed in a circular path. The instantaneous velocity and instantaneous acceleration vectors are
Perpendicular to each other
A ball is in free fall. Upward is taken to be the positive direction. The displacement of the ball during a short time interval is
Positive during ascent and negative during descent
The wound spring of a clock possesses
Potential but no kinetic energy
A block is attached to each end of a rope that passes over a pulley suspended from the ceiling, the blocks do not have the same mass. If the rope does not slip on the pulley, then at any instant after the blocks start moving the rope
Pulls on both blocks but exerts a greater force on the heavier block
A professor holds an eraser against a vertical chalkboard by pushing horizontally on it. He pushes with a force that is much greater than is required to hold the eraser. The force of friction exerted by the board on the eraser increases if he
Pushes so his force is slightly downward but has the same magnitude
A brick slides on a horizontal surface, which will increase the magnitude of the frictional force on it
Putting a second brick on top
Velocity is defined as
Rate of change of position with time
Acceleration is defined as
Rate of change of velocity with time
The inertia of a body tends to cause the body to
Resist any change in its motion
Which of the following is a scalar quantity
Speed
The rotational inertia of a wheel about its axle does not depend upon its
Speed of rotation
A bullet shot horizontally from a gun
Strikes the ground at approximately the same time as one dropped vertically from the same point at the same instant
Two bodies are falling with negligible air resistance side by side above a horizontal plane. If one of the bodies is given an additional horizontal acceleration during its descent, it
Strikes the plane at the same time as the other body
A feather, initially at rest, is released in a vacuum 12m above the surface of the earth. Which of the following statements is correct
The acceleration of the feather remains constant during the fall
Which one of the following statements is correct for an object released from rest
The average velocity during the first second of time is 4.9 m/s
A lead block is suspended from your hand by a string. The reaction to the force of gravity on the block is the force exerted by
The block on earth
The angular velocity vector of a spinning body points out of the page . If the angular acceleration vector points into the page then
The body is slowing down
The reaction force does not cancel the action force because
They are on different bodies
A car travels east at constant velocity. The net force on the car is
Zero
A cart loaded with sand slides forward along a horizontal frictionless track. As the cart moves, sand trickles out at a constant rate through a hole in the back of the cart. The acceleration of the cart is
Zero
A heavy steel ball b is suspended by a cord from a block of wood w. The entire system is dropped through the air. Neglecting air resistance, the tension in the cord is
Zero
A line drive to the shortstop is caught at the same height as it was originally hit. Over its entire flight the work done by gravity and the work done by air resistance respectively are
Zero negative
A baseball is thrown vertically into the air. The acceleration of the ball at its highest point is
g, down
A newton is the force
That gives a 1 kg body an acceleration of 1 m/s^2
The amount of work required to stop a moving object is equal to
The kinetic energy of the object
An elevator is rising at constant speed consider following statements
1 2 and 4 are true
The velocity of a projectile equals its initial velocity added to
A constantly increasing downward velocity
Uniform circular motion is the direct consequence of
A force of constant magnitude that is always directed toward the same fixed point
An example of an inertial reference frame is
A frame attached to a particle on which there are no forces
For a two body collision involving objects with different masses a frame of reference which has the same velocity relative to the laboratory as does the center of mass of the two objects is
A frame for which the total momentum of the two objects is zero
If the total momentum of a system is changing
A net external force must be acting on the system
A good example of kinetic energy is provided by
A tornado
A force with a given magnitude is to be applied to a wheel. The torque can be maximized by
Applying the force at the rim , tangent to the rim
The momentum of an object at a given instant is independent of its
Acceleration
In SI units a force is numerically equal to the _______ when the force is applied to it
Acceleration of the standard kilogram
Why do raindrops fall with constant speed during the later stages of their descent
Air resistance just balances the force of gravity
An object rests on a horizontal frictionless surface. A horizontal force of magnitude f is applied. This force produces an acceleration
Always
No kinetic energy is possessed by
An elevator standing at the fifth floor
A disk is free to rotate on a fixed axis. A force of given magnitude f in the plane of the disk is to be applied. Of the following alternatives the greatest angular acceleration is obtained if the force is
Applied tangentially at the rim
An object moves in a circle at constant speed. The work done by the centripetal force is zero because
Centripetal force is perpendicular to the velocity
The center of mass of the system consisting earth sun and planet mars is
Closer to the sun than to either of the other bodies
The coordinate time graph of an object is a straight line with a positive slope, the object has
Constant velocity
If the angular velocity vector of a spinning body points out of the page then, when viewed from above the page, the body is spinning
Counterclockwise about an axis that is perpendicular to the page
The area under a velocity time graph represents
Displacement
Which of the following groups does not contain a scalar quantity
Displacement acceleration force
A ball is in free fall. It's acceleration is
Downward during both ascent and decent
To increase the rotational inertia of a solid disk about its axis without changing its mass
Drill holes near the axis and put the material near the rim
A wheel starts from rest and spins with a constant angular acceleration. As time goes on the acceleration vector for a point on the rim
Increases in magnitude and becomes more nearly radial
A watt second is a unit of
Energy
Force
Equals the time rate of change of momentum
Compared to the windshield the airbag
Exerts a much smaller force
In raising an object to a given height by means of an inclined plane, as compared with raising the object vertically, there is a reduction in
Force required
A stone is tied to a string and whirled at constant speed in a horizontal circle. The speed is then doubled without changing the length of the string. Afterward the magnitude of the acceleration of the stone is
Four times as great
A disk starts from rest and rotates around a fixed axis subject to a constant net torque. The work done by the torque during the second 5s is ________ as the work done during the first 5s
Four times as much
An object is thrown vertically upward with a certain initial velocity in a world where the acceleration due to gravity is 19.6 m/s^2. The height to which it rises is ____ that to which the object would rise if thrown upward with the same initial velocity on the earth. Neglect friction.
Half
An object moving in a circle at constant speed
Has an acceleration of constant magnitude
The mass and weight of a body
Have the same ratio as that of any other body placed at that location
An object moving at constant velocity in an inertial frame must
Have zero net force on it
Which of the following is NOT an example of acceleration motion
Horizontal component of projectile motion
Two identical carts travel at 1m/s in opposite directions on a common horizontal surface. They collide head on and are reported to rebound each with a speed of 2m/s then
If some other form of energy were changed to kinetic during the collision, the report could be true
A body having constant velocity and variable accceleration
Impossible bitch
The vector of -A is
In the direction opposite to A
The sum of the kinetic and potential energies of a system of objects is conserved
None of the above
If a satellite moves above earths atmosphere in a circular orbit with constant speed then
It's acceleration is toward the earth
An object is shot vertically upward. While it is rising
It's velocity is upward and it's acceleration is downward
A force on a particle is conservative if
It's work depends on the end points of every motion, not on the path between
A ball is thrown upward into the air with a speed that is greater than terminal speed. It lands at the place where it was thrown. During its flight the force of air resistance is the greatest
Just after it is thrown
When the brakes of an automobile are applied, the road exerts the greatest retarding force
Just before the wheels start to slide
The SI base unit for mass is
Kilogram
An elastic collision is one in which
Kinetic energy and momentum are both conserved
A uniform solid cylinder made of lead has the same mass and the same length as a uniform solid cylinder made of wood. The rotational inertia of the lead cylinder compared to the wooden one is
Less
which of the following is not a vector
Mass
The physical quantity "impulse" has the same dimensions as that of
Momentum
An inelastic collision is one in which
Momentum is conserved but kinetic energy is not conserved
The thermal energy of a system consisting of a thrown ball, earth, and the air is most closely associated with
Motions of individual particles within the ball and the air
You stand on a spring scale on the floor of an elevator. The scale shows the highest reading when the elevator
Moves downward with decreasing speed
You stand on a spring scale on the floor of an elevator, the sale shows the highest reading when the elevator
Moves upward with increasing speed
The center of mass of earth atmosphere is
Near the center of earth
Throughout a time interval, while the speed of a particle increases as it moves along the x axis, its velocity and acceleration might be
Negative and negative, respectively
A baseball is hit high into the upper bleachers of left field. Over its entire flight the work done by gravity and the work done by air resistance respectively are
Negative negative
A nonconservative force
None of the above
If the magnitude of the sum of two vectors is greater than the magnitude of either vector then
None of the above
The coefficient of kinetic friction
None of the above
The average speed of a moving object during a given interval of time is always
The distance covered during the time interval divided by the time interval
The center of mass of a system of particles has a constant velocity if
The external forces acting on particles of the system sum to zero
When you step on the accelerator to increase the speed of your car, the force that accelerates the car is
The force of friction of the road on the tires
The thrust of a rocket is
The force of the exiting fuel gases on the rocket
A book rests on a table exerting a downward force on the table the reaction to this force is
The force of the table on the book
Identical guns fire identical bullets horizontally at the same speed from the same height above level planes, one on the earth and one on the moon. Which is true?
The horizontal distance traveled by the bullet is greater for the moon and the flight time is less for the bullet on the earth
A bomber flying in level flight with constant velocity releases a bomb before it is over the target. Neglecting air resistance, which is not true?
The horizontal velocity of the plane equals the vertical velocity of the bomb when it hits the target
When a particle suffers a head on elastic collision with another particle initially as rest the greatest fraction of kinetic energy is transferred if
The incident and target particle have the same mass
An object has a constant acceleration of 3 m/s^2. The coordinate versus time graph for this object has a slope
The increases with time
The magnitude of the acceleration of a point on a spinning wheel is increased by a factor of 4 if
The magnitude of the angular velocity is multiplied by a factor of 2 and the magnitude of the angular acceleration is multiplied by a factor of 4
The law of conservation of momentum applies to a system of colliding objects only if
The net external impulse is zero
Two uniform circular disks having the same mass and the same thickness are made from different materials. The disk with the smaller rotational inertia is
The one made from the more dense material
Two particles interact by conservative forces. In addition, an external force acts on each particle. They complete round trips, ending at the points where they started. Which of the following must have the same values at the beginning and end of this trip?
The potential energy of the two particle system
The mechanical advantage of any machine
The ratio of the force exerted by the machine to the force applied to it
A disk starts from rest and rotates about a fixed axis, subject to a constant net torque. The work done by the torque during the second of revolution is _______ as the work done during the first revolution
The same
A woman lifts a barbell 2 m in 5 s. If she lifts it the same distance in 10 s , the work done by her is
The same
A feather and a lead ball are dropped from rest in vacuum on the moon. The acceleration of the feather is
The same as that of the lead ball
Two bodies of unequal mass placed at rest on a frictionless surface are acted on by equal horizontal forces for equal times. Just after these forces are removed the body of greater mass will have
The same momentum as the other body
If the magnitude of the sum of two vectors is less than the magnitude of either vector, then
The scalar product of the vectors must be negative
The SI standard of length is based on
The speed of light
A free falling body has a constant acceleration of 9.8 m/s^2 this means that
The speed of the body increases by 9.8 m/s during each second
If a wheel turns with constant angular speed then
The wheel turns through equal angles in equal times
Given a potential energy function u the corresponding force f is in the positive x direction if
U is a decreasing function of x
A ball is thrown downward from the edge of a cliff with an initial speed that is three times the terminal speed. Initially it's acceleration is
Upward and greater than g
A car travels north at constant velocity. It goes over a piece of mud which it sticks to the tire. The initial acceleration of the mud as it leaves the ground is
Vertically upward
Which of the following five units represents a quantity that is not the same as the other four
Watt
Which of the following is not a correct unit for work
Watt
Mass differs from weight in that
Weight is a force and mass is not
A golf ball is struck by a golf club and falls on a green three meters above the tee. The potential energy of the earth ball system is greatest
When the ball reaches the highest point in its flight
A kilowatt hour is a unit of
Work
