P.O.T EXAM #03

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Whenever the net force of an object is zero it's acceleration
Is zero
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If an apple experience is a constant force, it will have a constant
Acceleration
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If you double the net force of an object, you'll double it's
Speed
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If the net force on a cart is tripled, the cart's acceleration
is three times as much
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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
5 N
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The force of friction on a sliding object is 10 N. The applied force needed to maintain a constant velocity is
10 N
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A 10-N falling object encounters 4 N of air resistance. The net force on the object is
6 N
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A 10-N falling object encounters 10 N of air resistance. The net force on the object is
0 N
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A 300-kg bear grasping a vertical tree slides down at constant velocity. The friction force between the tree and the bear is
3000 N
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The Newton is a unit of
force
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An object's weight is properly expressed in units of
newtons
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Which has the greater mass
an automobile battery
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A 1-kg mass at the Earth's surface weighs
10 N
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A kilogram is a measure of an object's
mass
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The mass of a lamb that weighs 110 N is about
11 kg
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The mass of a pet turtle that weighs 10 N is about
1 kg
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A bag of groceries that has a mass of 10 kilograms weighs about
100 N
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Compared to the mass of an apple on Earth, the mass of the apple on the Moon is
the same
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Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much
mass, inertia, and volume (ALL OF THE ABOVE)
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Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has the same
none of these
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the force due to gravity on you
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An object with twice as much mass as another object has twice as much
inertia
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Strange as it may seem, it is just as difficult to accelerate a car on a level surface on the Moon as it is here on Earth because
the mass of the car is independent of gravity
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In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the
moon
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At equilibrium on a bathroom weighting scale, the downward pull of gravity on you is balanced by
an upward support force
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When you stand at rest with your left foot on one bathroom scale and your right foot on a similar scale, each of the scales will
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A heavy ball hangs by a string, with a second string attached to its bottom. A quick pull on the bottom string breaks the
bottom string
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A heavy ball hangs by a string, with a second string attached to its bottom. A slow pull on the bottom string breaks the
top string
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When the bottom string is pulled slowly in the heavy-ball-and-strings demonstration (Figure 4.8 in your book), tension
in the top string is due to your pull plus the weight of the ball
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A rock weighs 30 N on Earth and another rock weighs 30 N on the Moon. Which rock has the greater mass?
the one on the moon
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A constant net force on a rail-road car produces constant
acceleration
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If an object's mass is decreasing while a constant force is applied to the object, the acceleration
increases
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If the mass of a cart is quickly loaded to have twice the mass while a propelling force remains constant, the cart's acceleration
halves
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An apple weighs 1 N. When the apple is held at rest above your head, the net force on the apple is
0 N
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An apple at rest weighs 1 N. The net force on the apple when it is in free fall is
1 N
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Which has zero acceleration? An object
at rest, moving at constant velocity, in mechanical equilibrium (ALL OF THE ABOVE)
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A car by itself is capable of a certain maximum acceleration. When it tows a twice-as-massive car, its maximum acceleration is
one half
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A car by itself iscapable of a certain maximum acceleration. When it tows a twice-as-massive car, its maximum acceleration is
one third
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You drive your car at a constant 60 km/h along the highway. You apply the brakes until the car slows to 40 km/h. If at that moment you suddenly release the brakes, the car tends to
continue moving at 40 km/h
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A heavy block at rest is suspended by a vertical rope. When the block accelerates upward by the rope, the rope tension
is greater than its weight
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If a non-rotating object has no acceleration, then we can say for certain that it is
in mechanical equilibrium
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A car has a mass of 1000 kg and accelerates at 2 m/s2. What net force is exerted on the car?
2000 N
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A tow truck exerts a force of 3000 N on a car, which then accelerates at 2 m/s2. What is the mass of the car?
1500 kg
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Nellie pulls on a 10-kg wagon with a constant horizontal force of 30 N. If there are no other horizontal forces, what is the wagon's acceleration?
3.0 m/s2
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A force of 1 N accelerates 1-kg box at the rate of 1 m/s2. The acceleration of a 2-kg box by a net force of 2 N is
the same
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The force required to maintain a constant velocity for an astronaut in free space is equal to
zero
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A boulder following a straight-line path at constant velocity has
zero acceleration
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Neglecting friction, a small and a large block of ice begin sliding down an incline together. The larger block reaches the bottom
at the same time as the small block
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Phil stands at rest with both feet on a scale that reads 500 N. When he gently lifts one foot, the scale reads
500 N
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A push on a 1-kg brick accelerates it. Neglecting friction, equally accelerating a 10-kg brick requires
10 times as much force
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A 10-N block and a 1-N block lie on a horizontal frictionless table. To impart equal horizontal accelerations, we should have to push the heavier block with
10 times as much force
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When a constant and sustained upward force acts on a rocket, its acceleration increases mainly because
the mass of the rocket decreases as fuel is burned
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A rock is thrown vertically into the air. At the top of its path the net force on it is
mg
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A rock is thrown vertically into the air. At the top of its path, its acceleration is
10 m/s^2
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A block is dragged without acceleration in a straight-line path across a level surface by a force of 6 N. What is the force of friction between the block and the surface?
6 N
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Suppose a particle is accelerated through space by a constant 10-N force. Suddenly the particle encounters a second force of 10-N in the opposite direction. The particle with both forces acting
continues at the speed it had when it encountered the second force
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A jumbo jet has a mass of 100,000 kg. The thrust for each of its four engines is 50,000 N. What is the jet's acceleration when taking off?
2 m/s^2
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A 1-kg rock that weighs 10 N is thrown straight upward at 20 m/s. Neglecting air resistance, the net force that acts on it when it is half way to the top of its path is
10 N
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If more horizontal force is applied to a sliding object than is needed to maintain a constant velocity, the object
accelerates in the direction of the applied force
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If less horizontal force is applied to a sliding object than is needed to maintain a constant velocity, the object
eventually slides to a stop
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A 1-kg ball is thrown at 10 m/s straight upward. Neglecting air resistance, the net force that acts on the stone when it is halfway to the top of its path is about
10 N
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The brakes of a speeding truck are slammed on and it skids to a stop. If the truck were heavily loaded so that it had twice the total mass, the skidding distance would be
the same
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Scotty Skydiver of mass 100 kg experiences air resistance of 500 N, and an acceleration of about
0.5 g
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An object released from rest on another planet requires one second to fall a distance of 6 meters. What is the acceleration due to gravity on this planet?
12 m/s2
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A car traveling at 22 m/s comes to an abrupt halt in 0.1 second when it hits a tree. What is the deceleration of the car?
220 m/s^2
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A 10-kilogram block with an initial velocity of 10 m/s slides 10 meters across a horizontal surface and comes to rest. It takes the block 2 seconds to stop. The stopping force acting on the block is about
50 N
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A 10-kilogram block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block is
1 m/s2
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If you are driving at 20m/s and slam on your brakes and skid at 0.5 to a full stop, like skidding time is about
4 s
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A 1000-kg automobile enters a freeway on-ramp at 20 m/s and accelerates uniformly up to 40 m/s in a time of 10 seconds. How far does the automobile travel during that time?
300 m
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A 2000-kg car experiences a braking force of 10,000 N and skids to a stop in 6 seconds. The speed of the car just before the brakes were applied was
30 m/s
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An astronaut on another planet drops a 1-kg rock from rest and finds that it falls a vertical distance of 2.5 meters in one second. On this planet, the rock has a weight of
5 N
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What horizontally-applied force will accelerate a 400-kg crate at 1 m/s2 across a factory floor against a friction force half its weight?
2400 N
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The human body can withstand an acceleration of 10 g under certain conditions. What net force would produce this acceleration for a 50-kg person?
5000 N
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A 10-kg brick and a 1-kg apple are dropped in a vacuum. The force of gravity on the brick is
10 times more than the force on the apple
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A single brick falls with acceleration g. The reason a double brick falls with the same acceleration is
its ratio of force to mass is the same
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Recall Galileo's Leaning Tower experiment. With negligible air resistance, a heavy and a light object fall
with equal accelerations, to the ground in equal times, with the same increases in speed (ALL OF THE ABOVE)
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A feather and a coin will have equal accelerations when falling in a vacuum because
the ratio of both the feather's and coin's weight to mass is the same.
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A bowling ball and a baseball accelerate equally when falling in a vacuum because
the ratio of their weights to mass is the same.
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An astronaut on another planet drops a 1-kg rock from rest. The astronaut notices that the rock falls 2 meters straight down in one second. On this planet, how much does the rock weigh?
4 N
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Two factors that greatly affect air resistance on falling objects are frontal area and
speed
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When a falling object has reached its terminal velocity, its acceleration is
zero
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Two objects of the same size, but unequal weights are dropped from a tall tower. Taking air resistance into consideration, the object to hit the ground first will be the
heavier object
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A light woman and a heavy man jump from an airplane at the same time and open their same-size parachutes at the same time. Which person will get to a state of zero acceleration first?
the light woman
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A light woman and a heavy man jump from an airplane at the same time and open their same-size parachutes at the same time. Which person will get to the ground first?
The heavy man
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A large and a small person wish to parachute at equal terminal velocities. The larger person should
get a larger parachute
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A coconut and a bird's feather fall from a tree through the air to the ground below. The force of air resistance is
greater on the coconut
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Suzie Skydiver jumps from a high-flying plane. As her velocity of fall increases, her acceleration
decreases
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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, the sack's acceleration becomes
0 m/s2
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A skydiver steps from a helicopter and falls for a few seconds until terminal velocity is reached. Thereafter, until he opens his parachute, his acceleration
is zero
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A 500-N parachutist opens his chute and experiences an air resistance force of 800 N. The net force on the parachutist is
300 N upward
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A ball is thrown vertically into the air. Because of air resistance it's speed when it returns to Its starting starting level compared with its initial speed is
Less
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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, the sack's acceleration becomes
0 m/s2
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Two tennis balls fall through the air from a tall building. One of them is filled with lead pellets. The ball to reach the ground first is the
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A heavy rock and a light rock of the same size are falling through the air from a tall building. The one that encounters the greatest air resistance is the