Physics chapter 4
The mass of a pet turtle that weighs 10 N is about
1 kg.
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
The force of friction on a sliding object is 10 N. The applied force needed to maintain a constant velocity is
10 N
A rock is thrown vertically into the air. At the top of its path, its acceleration is
10 m/s2
A push on a 1-kg brick accelerates it. Neglecting friction, equally accelerating a 10-kg brick requires
10 times as much force.
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.
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
A car has a mass of 1000 kg and accelerates at 2 m/s2. What net force is exerted on the car?
2000 N
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
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
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
If you are driving at 20 m/s and slam on your brakes and skid at 0.5g to a full stop, the skidding time is about
4 s
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
Suzie Skydiver, who weighs 500 N, reaches terminal velocity of 90 km/h. The air resistance on Suzie is then
500 N
A skydiver's terminal velocity will be greatest if she falls
head first
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
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
heavy rock
If an object's mass is decreasing while a constant force is applied to the object, the acceleration
increases
An object with twice as much mass as another object has twice as much
inertia
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.
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
A ball is thrown vertically into the air. Because of air resistance, its speed when it returns to its starting level compared with its initial speed is
less
A kilogram is a measure of an object's
mass.
A ball is thrown vertically into the air. Because of air resistance, its time coming down compared to its time going up is
more
Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has the same
none of the above
A car by itself is capable of a certain maximum acceleration. When it tows a twice-as-massive car, its maximum acceleration is
one third
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
show readings that when added equal your weight
Two factors that greatly affect air resistance on falling objects are frontal area and
speed
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.
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
A bowling ball and a baseball accelerate equally when falling in a vacuum because
the ratio of their weights to mass is the same
Compared to the mass of an apple on Earth, the mass of the apple on the Moon is
the same.
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.
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
The force required to maintain a constant velocity for an astronaut in free space is equal to
zero.
If an apple experiences a constant net force, it will have a constant
acceleration
Recall Galileo's Leaning Tower experiment. With negligible air resistance, a heavy and a light object fall
all of the above
Which has zero acceleration? An object
all of the above
Which has the greater mass?
an automobile battery
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.
In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the
Moon
A 10-N falling object encounters 10 N of air resistance. The net force on the object is
0 N
An apple weighs 1 N. When the apple is held at rest above your head, the net force on the apple is
0 N
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
Suppose a particle is being accelerated through space by a 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.
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.
The newton is a unit of
force
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
