PHYSICS CONCEPT FINAL
the coefficient of kinetic friction
none of the above
whenever an object strikes a stationary object of equal mass:
none of the above
An astronaut on the Moon simultaneously drops a feather and a hammer. The fact that they land together shows that:
in the absence of air resistance all bodies at a given location fall with the same acceleration
the principle of fluid pressure which is used in hydraulic brakes or lifts is that:
increases of pressure are transmitted equally to all parts of a fluid
during a short interval of time the speed v in m/s of an automobile is given by v=at2 +bt3, where the time t is in seconds. The units of a and b are respectively:
m/s3 , m/s4
An inelastic collision is one in which
momentum is conserved but kinetic energy is not conserved
a rifle of mass M is initially at rest but free to recoil. it fires a bullet of mass m and velocity v (relative to the ground). after firing, the velocity of the rifle (relative to the ground) is:
-mv/M
Sphere A has mass m and is moving with velocity v. It makes a head-on elastic collision with a stationary sphere B of mass 2m. After the collision their speeds (vA and vB) are:
-v/3, 2v/3
A vector of magnitude 3 CANNOT be added to a vector of magnitude 4 so that the magnitude of the resultant is:
0
A boy holds a 40 N weight at arm's length for 10 s. His arm is 1.5 m above the ground. The work done by the force of the boy on the weight while he is holding it is
0 J
A 1000 kg airplane moves in flight at constant speed. The force of air friction is 1800 N the net force on the plane is:
0 N
A car starts from Hither, goes 50 km in a straight line to Yon, immediately turns around, and returns to Hither. The time for the round trip is 2 hours. The magnitude of the average velocity of the car for this round trip is
0 km/h
Multiplying a 2 significant figure number by a 3 significant figure number and then diving the product by a 6 significant figure number yields a number with how many significant figures?
2
The number 0.00017 has how many significant figures?
2
which of the following is a correct statement of Newton's first law?
An object in motion will continue in motion at a constant velocity unless acted on by a net external force
A wrench is dropped from the top of a 10 m mast on a sailing ship while the ship is traveling at 20 mph. The wrench will hit the deck
At the bottom of the mast
A baseball catcher throws a ball vertically upward and catches it in the same spot when it returns to his mitt. At what point in the ball's path does it experience zero velocity and non-zero acceleration at the same time?
At the top of its trajectory
Vectors A and B lie in the xy plane. We can deduce that A=B if
Ax = Bx and Ay = By
power has the dimensions of
ML2/T3
the gravitational constant G has the derived units
Nm^2/kg^2
a feather, initially at rest, is released in a vacuum 12 m above the surface of the Earth. Which of the following statements is correct?
The acceleration of the feather remains constant during the fall
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
Which formula is dimensionally consistent with an expression yielding a value for velocity?
at
ow can you throw a projectile so that it has zero speed at the top of its trajectory?
at an angle equal to 90 degrees to the horizontal
Jeff throws a ball straight up. For which situation is the vertical velocity zero?
at the top
A baseball is thrown by the center fielder (from shoulder level) to home plate where it is caught (at shoulder level) by the catcher. At what point is the ball's speed at a minimum?
at the top of the trajectory
a ball is thrown vertically upward in the air. which of the following quantities is necessarily equal to zero at the highest point of the balls trajectory?
kinetic energy
An elastic collision is one in which:
kinetic energy and momentum are both conserved
The amount of work required to stop a moving object is equal to the:
kinetic energy of the object
the work done by gravity during the descent of a projectile is
positive
in a stationary homogeneous liquid
pressure is the same at all points at the same level
A brick slides on a horizontal surface. Which of the following will increase the frictional force on it?
putting a second brick on top of it
A tennis player on serve tosses a ball straight up. While the ball is in free fall, its acceleration:
remains constant
A loaded ship passes from a lake (fresh water) to the ocean (saltwater). Saltwater is more dense than fresh water and as a result the ship will:
ride higher in the water
A person blows across the top of one arm of a U-tube partially filled with water. The water in that arm:
rises slightly
Consider a pipe containing a fluid, with the fluid being at rest. To apply Bernoulli's equation to this situation:
set v equal to zero because there is no motion
A train car moves along a long straight track. The graph shows the position as a function of time for this train. The graph shows that the train:
slows down all the time
Vector A is 3 m long and vector B is 4 m long. The length of the sum of the vectors must be:
some value from 1 m - 7 m
Vector A points north and vector B points east. If C=B-A then vector C points:
south of east
water flows through a constriction in a horizontal pipe. as it enters the constriction, the water's
speed increases and pressure decreases
the rotational inertia of a wheel about its axle does not depend upon its
speed of rotation
a force is applied to a billiard ball. in order to calculate the torque created by the force you also need to know
the location and orientation of the axis of rotation of the ball
instantaneous angular speed is
the magnitude of the instantaneous angular velocity
if a projectile hits a stationary target and the projectile rebounds and travels back the way it came,
the mass of the projectile is much less than the mass of the target
mass differs form weight in that:
weight is a force and mass is not
30 degrees is
π/6 radians
Which one of the choices below represents the preferred practice regarding significant figures when adding the following: 12.4+11+67.37+4.201?
95
the "reaction" force does not cancel the "action" force because
they act on different bodies
a kilowatt hour is a unit of:
energy
A forward horizontal force of 12 N is used to pull a 240-N crate at constant velocity across a horizontal floor. The coefficient of friction is:
0.05
Which of the following weighs about a pound on Earth?
0.5 kg
An object moves 20 m east in 30 seconds and then returns to its starting point taking an additional 50 seconds. If west is chosen as the positive direction, what is the average speed of the object?
0.50 m/s
an object rotates from 01 to 02 through an angle that is less than 2pi radians. which of the following represents its angular displacement
02 - 01
one watt is
1 kg x m2/s3
1 Pa is
1 kg/ m x s2
The prefixes which are abbreviated p,n, and G represent which of the following?
10-12, 10-9, 109
A square with an edge of exactly 1 cm has an area of:
10-4 m2
The length and width of a standard sheet of paper is measured, and then the area is found by calculation to be 93.5 inch squared. The number of significant figures in the width measurement must be at least:
10-4 m2
Estimate the number of atoms in 1 cm3 of a solid (diameter of an atom is about 10-10 m)
10e24
One tonne (metric ton) is 1000 kg. How many grams are there in one tonne?
10e6
a 1100 kg elevator is rising and its speed is increasing at 3.0 m/s2. the tension in the elevator cable is
14000 ---> (m x g) + (m x v)
one revolution is the same as
2 pi radians
an object moves in a circle, if the mass is tripled, the speed halved and the radius unchanged then the magnitude of the centripetal force must be multiplied by a factor of:
3/4
Remembering rules concerning significant figures, 2.22+2.443 is equal to:
4.66
a block slides down a frictionless plane that makes an angle of 20 degrees with the horizontal. the acceleration of the block is:
4.9 m/s2 a=gsin theta
Remembering rules concerning significant figures, 9.5・4.53 is equal to
43
roughly what is your weight
600 N
A vector in the xy plane has a magnitude of 25 and an x component of 12. The angle it makes with the positive x axis is:
61 degrees (take inverse cos)
a 5 kg object can move along the x-axis. it is subjected to a force F in the positive x direction; a graph of F as a function of time t is shown below. over the time the force is applied the change in the velocity of the object is
= the area divided by mass
If you drop a rock and a feather, the rock hits the ground first. This demonstrates that:
Air resistance has a larger effect on feathers than on rocks
An incompressible liquid flows along the pipe as shown. The ratio of the speeds v2/v1 is:
A1/A2
the plot shows the force acting on an object as a function of time. over the time the force is applied, the total impulse is
AREA ONLY
Two objects of different mass are released simultaneously from the top of a 20 meter tower and fall to the ground. If air resistance is negligible, which statement best applies?
Both objects hit the ground together.
a man pulls a sled along a rough horizontal surface by applying a constant force F at an angle above the horizontal. in pulling the sled a horizontal distance d, the work done by the man is
Fd cos theta
An object is dropped from a height. Once it is moving, which of the following statements is true, at least at one point?
Its velocity is never equal to its acceleration
the hydraulic automobile jack illustrates
Pascal's principle
What is the difference between speed and velocity?
Speed is the magnitude of velocity; velocity is a vector and has both magnitude and direction
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
Suppose A=BC, where A has the dimensions L/M and C has the dimensions L/T. Then B has the dimension:
T/M
uniform circular motion is the direct consequence of:
a force of constant magnitude that is always directed toward the same fixed point
Which of the SI standard units is NOT based on a constant of nature?
The kilogram, because it is based on an arbitrary piece of metal
A freely falling body has a constant acceleration of 9.8 meters per second squared. This means that:
The speed of the body increases 9.8 meters per second during each second
a nonconservative force
a force whose work depends on the path followed between the given initial and final configurations
If the total momentum of a system is changing:
a net external force must be acting on the system
if the total momentum of a system is changing:
a net external force must be acting on the system
the gravitational constant G
a proportionality factor used in the equation for Newton's universal law of gravitation; it is a universal constant—that is, it is thought to be the same everywhere in the universe
An object is moving with constant non-zero velocity in the +x axis. The position versus time graph of this object is
a straight line making an angle with the time axis
Which one of the following statements is correct?
a streamline is the path that a tiny element of fluid would take as the fluid flows
You are throwing a ball straight up in the air. At the highest point, the ball's
acceleration is nonzero, but the velocity is zero
A baseball is thrown by a center fielder from shoulder level to home plate where it is caught at shoulder level by the catcher. At what point is the magnitude of the acceleration at a minimum?
acceleration stays constant throughout the entire trajectory
To obtain the absolute pressure from the gauge pressure:
add atmospheric pressure
Why do raindrops fall with constant speed during the later stages of their descent?
air resistance just balances the force of gravity
in a one-dimensional collision
all motion, both before and after the collision, must be along the same line
The vessels shown below all contain water to the same height. Rank them according to the pressure exerted by the water on the vessel bottoms, least to greatest.
all pressure are the same
The graph shows position as a function of time for two trains running on parallel tracks. Which is true:
both trains have the same velocity at some time before tb
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
A ball is thrown upwards. Its acceleration is:
downward during both ascent and descent
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
An object goes from one point in space to another. After it arrives at its destination, its displacement is________ to the distance it traveled.
either smaller or equal to
a watt-second is a unit of
energy
force:
equals the time rate of change of momentum
A student's life was saved in an automobile accident because an airbag expanded in front of his head. If the car had not been equipped with an airbag, the windshield would have stopped the motion of his head in a much shorter time. Compared to the windshield, the airbag:
exerts a much smaller force
t = Ia for an object rotating about a fixed axis, where t is the net torque acting on it, I is its rotational inertia, and a is its angular acceleration. This expression:
follows directly from Newton's second law
A baseball is thrown vertically into the air. The acceleration of the ball at its highest point is:
g, down
all fluids are
gases or liquids
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
an object moving in a circle at constant speed:
has an acceleration of constant magnitude
water is pumped through the hose shown, from a lower level to an upper level. compared to the water at point1 the water at point 2
has greater speed and less pressure
an object moving at constant velocity in an inertial frame must:
have zero net force acting on it
the pressure exerted on the ground by a man is greatest when:
he stands on the toes of one foot
In the formula F = Gm1m2/r^2, the quantity G:
is a universal constant of nature
Harrison pushes a heavy box across the room floor. the work done by gravity on the box
is equal to zero
a woman holds a bowling ball in a fixed position. the work she does on the ball
is equal to zero
Two objects, P and Q, have the same momentum. Q has more kinetic energy than P if it:
is moving faster than p
A non-viscous incompressible liquid is flowing through a horizontal pipe of constant cross section. Bernoulli's equation and the equation of continuity predict that the drop in pressure along the pipe:
is zero
Mercury is a convenient liquid to use in a barometer because:
it has a high density
If a satellite moves above the Earth's atmosphere in a circular orbit with constant speed, then:
its acceleration is toward the Earth
a force on a particle is conservative if:
its work depends on the end points of every motion, not on the path between
Which of the following 5 quantities is NOT an expression for energy? here m is a mass, g is the acceleration due to gravity, h and d are distances, F is a force, v is a speed .....etc
ma (expression for Force)
which of the following bodies has the largest kinetic energy?
mass 2M and Speed 3V
A block of mass m is pulled along a horizontal floor by an applied force T as shown. The vertical component of the force exerted on the block by the floor is:
mg - T sin theta
the physical quantity 'impulse' has the same dimensions as
momentum
You stand on a spring scale on the floor of an elevator. Of the following, the scale shows the highest reading when the elevator:
moves downward with decreasing speed
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
which of the following assumptions is NOT made in the derivation of Bernoulli's equation?
neglect gravity
A ball is thrown vertically upwards at 19.6 m/s. For its complete trip (up and back down to the starting position), its average velocity is:
not given cause equal to 0
acceleration is always in the direction
of the net force
As a projectile moves in its parabolic path, the velocity and acceleration vectors are perpendicular to each other
only at the peak of its path
The vector -A is:
opposite direction of A
A boy pulls a box along horizontal floor at constant speed by means of a force p. f is the magnitude of the force of friction, N is the magnitude of the normal force, and Fg is the magnitude of the force of gravity. what must be true?
p = f, N=Fg
The slope of the curvature in the position vs. time graph for particle's motion gives
particle's instantaneous velocity
in uniform circular motion
the acceleration and the velocity are always perpendicular
which of the following is true, according to Newton's second law?
the acceleration of an object is proportional to the force and inversely proportional to its mass
An object hangs from a spring balance. The balance indicates 30N in air and 20N when the object is submerged in water. What does the balance indicate when the object is submersed in a liquid with a density that is half that of water?
the actual weight of the object is slightly more than 30 N, due to the buoyant force of the air
an object moves in a circle at constant speed. the work done by centripetal force is zero because:
the centripetal force is perpendicular to the velocity
a fluid is undergoing "incompressible" flow. this means that:
the density cannot change with time or location
The average speed of a moving object during a given interval of time is always:
the distance covered during time interval divided by the time interval
the unit of force called the newton is
the force needed to accelerate a mass of 1 kg at a rate of 1 m/s2
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
the law of conservation of momentum applies to a system of colliding objects only if:
the net external impulse is zero
several cans of different sizes and shapes are all filled with the same liquid to the same depth. then:
the pressure on the bottom of each can is the same
a disk is rotating at a constant rate about a vertical axis through its center. Point Q is twice as far from the center of the disk as point P is. the angular velocity of Q at a given time is
the same as P's
a fluid is undergoing steady flow. therefore:
the velocity at any given point does not vary with time
If a wheel turns with constant angular speed then:
the wheel turns through equal angles in equal times
"An object completely submerged in a fluid displaces its own volume of fluid". This is:
true, but not a principle
the momentum of an object at a given instant is in the same direction as its
velocity
which of the following is NOT a correct unit for work?
watt
a golf ball is struck by a golf club and falls on a green eight feet above the tee. the potential energy of the Earth-ball system is greatest
when the ball reaches the highest point in its flight
As a projectile thrown at some angle with respect to the horizontal moves in its path, is there any point along the path where the velocity and the acceleration are perpendicular to each other?
yes, at the top of the trajectory
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