physics exam 1
a bullet is dropped form the top of a very tall skyscraper while another bullet is fired downward from the same place. neglecting air resistance, acceleration is greatest for... A) fired B) dropped C) ... is 10 m/s^2 for each D) depends on the height above the ground
... is 10 m/s^2 for each
an apple weighs 1 N. when held above your head, the net force on the apple is... A) 0 N B) 0.1 N C) 1 N D) 9.8 N E) none of these
0 N
a sack of potatoes weighing 200 N falls from an airplane. as the velocity of fall increases, air resistance also increases. when air resistance equals 200 N, what's the sack's acceleration? A) 0 m/s^2 B) 4.9 m/s^2 C) 10 m/s^2 D) infinite E) none of these
0 m/s^2
a falling skydiver of mass 100 kg experiences 600 N of air resistance. what's her acceleration? (for this problem, g = 10 m/s^2) A) 0.2 g B) 0.3 g C) 0.4 g D) 0.5 g E) none
0.4 g
an apple weighs 1 N. the net force on the apple when it's in free fall is... A) 0 N B) 0.1 N C) 1 N D) 9.8 N E) none of these
1 N
the mass of a dog that weighs about 100 N is about... A) 1 kg B) 10 kg C) 100 kg D) 1000 kg E) none of these
10 kg
if a freely-falling object were somehow 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
10 m/s
if you drop an object, it will accelerate downward at a rate of 10 m/s^2. if you instead throw it downwards, its acceleration will be... A) greater than 10 m/s^2 B) less than 10 m/s^2 C) 10 m/s^2
10 m/s^2
a 10 kg brick and a 1 kg book are dropped in a vacuum. the force of gravity on the 10 kg brick is... A) the same as the force on the 1 kg book B) 10 times as much as the force on the 1 kg book C) zero
10 times as much as the force on the 1 kg book
a man falling through the air with a parachute weighs 500 N. when he opens the chute, he experiences an initial air resistance force of 800 N. the net force on the man is... A) 300 N downward B) 500 N downards C) 800 N downward D) 300 N upward E) 500 N upward
300 N upward
a package falls off a truck that's moving 40 m/s horizontally. neglecting air resistance, the horizontal speed of the package just before it hits the ground is... A) less than 40 m/s B) zero C) 40 m/s D) more than 40 m/s
40 m/s
two people pull on a rope in a tug of war. each pulls with 400 N of force. what's the tension in the rope? A) zero B) 400 N C) 600 N D) 800 N E) none of these
400 N
an object in free fall moving is the vertical direction only. at one instant, it is traveling at a speed of 55 m/s. exactly 1 second later its speed is about... A) 65 m/s^2 B) 45 m/s C) 10 m/s D) 9.8 m/s E) 60 m/s
45 m/s
a person is attracted towards the center of the earth by a 500 N gravitational force. the force that the earth is attracted toward the person... A) very small B) very very large C) 500 N
500 N
a 10 N falling object encounters 4 N of air resistance. the magnitude of the net force on the object is... A) 0 N B) 4 N C) 6 N D) 10 N E) none of these
6 N
a man weight 800 N stands on two bathroom scales; one foot on each scale. the reading on one scale is given to be 200 N, so the reading on the other scale is... A) 700 N B) 400 N C) 800 N D) 600 N E) none of these
600 N
a car accelerates at 3 m/s^2. what's the speed 3 seconds after the car starts moving from rest? A) 6 m/s B) 9 m/s^2 C) 9 m/s D) 12 m/s
9 m/s
among other things, newton's third law states that... A) it is impossible that only one force acts on a body B) forces acting on a single body only occur in pairs C) a horse can't make a wagon accelerate D) a force is an interaction between two bodies
a force is an interaction between two bodies
when an object is projected straight up and eventually falls back down, if you include air resistance, then the time it will take for the object to travel upward compared to its time to make the same distance trip downward is... A) same time for both directions B) a longer time on the way up and a shorter time on the way down C) a longer time on the way down and a shorter time on the way up D) a longer time on the way down and a longer time on the way up
a longer time on the way down and a shorter time on the way up
disregarding air resistance, objects fall at constant... A) velocity B) speed C) acceleration D) distances each successive second E) all of these
acceleration
a 100 N bag of groceries is at rest on the ground. how much force is necessary to make the groceries accelerate upward... A) greater than 100 N B) less than 100 N C) 100 N D) anything greater than 100 N
anything greater than 100N
concerning gravitation mass and inertial mass... A) inertial mass and gravitational mass are the same numbers B) gravitational and inertial mass are the same ideas C) gravitational and inertial are different ideas D) both a and c E) both a and b
are the same numbers but different ideas
a heavy object and a light object are dropped at the same time from rest in a vacuum. the heavier object reaches the ground... A) sooner than the light object B) at the same time as the lighter object C) later than the lighter object
at the same time as the lighter object
if an object falls with constant acceleration, the velocity of the object must... A) be constant also B) continually be changing by the same amount each second C) continually change by varying amounts depending on its speed at any point D) continually decrease
continually be changing by the same amount each second
suppose a particle is accelerated through space (no gravity) by a 10 N force. suddenly the particle encounters a second force of 10 N in the opposite direction of the first force while the first force is still present. the particle... A) is brought to a rapid halt B) decelerates gradually to a halt C) continues at the speed it had when it encountered the second force D) theoretically accelerates to speeds approaching the speed of light in the absence of a net force
continues at the speed it had when it encountered the second force
when an object falls through the air, its velocity increases and its acceleration... A) increases B) decreases C) remains the same whether in air or vacuum
decreases
a truck is moving at constant velocity. inside the storage compartment, a rock is dropped from a midpoint of the ceiling and strikes the floor below. the rock hits the floor... A) exactly below the midpoint of the ceiling B) ahead of the midpoint of the ceiling C) behind the midpoint of the ceiling D) more information is needed to solve this problem E) none of these
exactly below the midpoint
your weight is a measure of your... A) momentum B) energy C) gravitational attraction to the earth D) rotational equilibrium
gravitational attraction to the earth
an object following a straight-line path at constant speed... A) has a net force acting upon it in the direction of motion B) has zero acceleration C) must be moving in vacuum D) has no forces acting on it E) none of the above
has zero acceleration
when you start to walk after standing at rest, the force of friction of the ground on you is... A) opposite the direction in which you walk B) opposite the normal force on you C) in the same direction as you are walking
in the same direction as you are walking
mass is a measure of an object's... A) weight B) force C) gravity D) inertia
inertia
one object has twice as much mass as another object. the first object also has twice as much (remember, as an object's speed increases its mass is relative to you also increases)... A) inertia B) velocity C) energy D) all of these
inertia
compared to its weight on earth, a 10 kg object on the moon will weigh... A) less B) more C) the same
less
an object maintains its state of motion b/c it has... A) mass B) force C) speed D) acceleration E) all of these
mass
a feather and a coin will have equal accelerations when falling in a vacuum (no air resistance) because... A) their velocities are the same B) gravity does not act in a vacuum C) the ratio of these object's weight to mass is the same D) none of these
none of these
what is required to keep an asteroid moving for billions of years out in deep space? A) gravity B) inertia C) force D) nothing
nothing
when a very massive object collides with a small mass... A) on impact the masses experience different forces B) on impact the more massive object experiences the greater force C) on impact the less massive object experiences the greater force because of its greater deceleration D) on impact the force on each mass are the same but the more massive object experiences smaller acceleration
on impact the forces on each mass are the same but the more massive object experiences a smaller acceleration
newton's third law says that... A) only an even number of forces can be exerted on a body B) only an even number of total forces (occurring in pairs) exist in the universe C) only an odd number of forces can exist in the universe D) nonsense! any number of forces can exist in the universe
only an even number of total forces (occurring in pairs) exist in the universe
in which case would the bottom of a paper bag carrying groceries by most likely to be ripped open? A) the bag of groceries is accelerated upwards B) the bag of groceries is moving upward with a large but constant velocity C) the bag of groceries is accelerating downwards D) the bag of groceries is stationary
the bag of groceries is accelerated upward
if the velocity of a body and its acceleration are oppositely directed, then... A) the body speeds up B) the body will slow down C) the body changes direction D) the body has a negative acceleration
the body will slow down
if a body is speeding up, then you know that... A) the body's velocity is anti-parallel to its displacement B) the body's velocity is parallel to its acceleration C) the body's velocity is opposite to its accelertaion D) the body's velocity is parallel to its speed
the body's velocity is parallel to its acceleration
an object weighs 30 N on Earth. a second object weighs 30 N on the moon. which has a greater mass? A) the one on the earth B) the one on the moon C) they have the same mass D) not enough information to say
the one on the moon
as a ball falls, the action force is the pull of the earth's mass on the ball. what's the reaction to this force? A) the air resistance acting against the ball B) the acceleration of the ball C) the pull of the ball's mass on the earth D) non-existent in this case E) none of these
the pull of the ball's mass of the earth
compared to its mass on earth, the mass of an object on the moon is... A) less B) more C) the same
the same
newton's 2nd law says that if the acceleration of a body is zero then... A) number of forces acting on a body must be zero B) the body has no change in velocity by newton's first law C) the vector sum of all the forces acting on a body must be zero D) it can have any value for its mass
the vector sum of all forces acting on the body must be zero
a horse exerts 500 N of force on a heavy wagon. the wagon pulls back on the horse with an equal force. the wagon still accelerates b/c... A) these two forces are not an action-reaction pair B) the horse pulls on the wagon a brief time before the wagon reacts C) there is still a net force acting on the wagon D) the wagon does not acceleration b/c these forces are equal and opposite E) none of these
there is still a net force acting on the wagon
a moving object on which no forces are acting on it will continue to move with constant... A) non-zero acceleration B) speed C) velocity D) all of the above E) none of the above
velocity
as an object freely falls, its... A) velocity changes direction B) acceleration increases C) both of the above D) velocity changes
velocity changes
when a rock thrown straight upwards gets to the exact top of its path, its... A) velocity is zero and acceleration is zero B) velocity is zero and acceleration is 10 m/s^2 C) velocity is 10 m/s and acceleration is zero D) velocity is 10 m/s and acceleration is 10 m/s^2
velocity is zero and its acceleration is about 10 m/s^2
a mack truck and a volkswagen traveling at the same speed have a head-on collision. vehicle to undergo greatest change in velocity will be the... A) volkswagen B) mac truck C) both the same
volkswagen