Conceptual Physics (TESC) Chapter 4

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 in meters per second per second when taking off

2

A car has a mass of 1000 kg and accelerates at 2 meters per second per second. What is the magnitude of the net force exerted on the car

2000 N

When a woman stands at rest with both feet on a scale, it reads 500 N. When she gently lifts one foot, the scale reads

500 N.

A skydiver of mass 100 kg experiences air resistance of 500 N, and an acceleration of

about 0.5 g.

A bag of groceries has a mass of 10 kilograms and a weight of

about 100 N.

If you are driving at 20 m/s and slam on your brakes and skid at 0.5 g to a full stop, the skidding time in seconds is

about 4.

If an object of constant mass experiences a constant net force, it will have a constant

acceleration

Your car is coasting on level ground at 60 km/h and you apply the brakes until the car slows to 40 km/h. If you suddenly release the brakes now, the car tends to

continue moving at 40 km/h.

A ride on a roller-coaster car containing 6 passengers takes 3 minutes. Neglecting friction, a similar ride with 12 passengers aboard would take

3 minutes.

A girl 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 in meters per second per second

3.0

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.

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

A man weighing 800 N stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is

400 N.

An object is pulled northward by a force of 10 N and at the same time another force of 15 N pulls it southward. The magnitude of the resultant force on the object is

5 N.

An apple at rest weighs 1 N. The net force on the apple when it is in free fall is

1 N.

The force of friction on a sliding object is 10 newtons. The applied force needed to maintain a constant velocity is

10 N.

A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is

10 times as much.

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

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

Which has zero acceleration? An object

At rest0; moving at constant velocity; and in mechanical equilibrium.

When you relax at rest with your left foot on one bathroom scale and your right foot on a similar scale, each of the scales will

Indicate exactly half your weight; indicate part of your total weight but not necessarily half of it and indicate different values that will equal your weight when added together

Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much

Inertia, Mass, and Volume

When a falling object has reached its terminal velocity, its acceleration is

Zero

A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is

equal to its weight.

A force of 1 N accelerates a mass of 1 kg at the rate of 1 m/s2. The acceleration of a mass of 2 kg acted upon by a net force of 2 N is

the same.

Compared to the mass of a certain object on Earth, the mass of the same object on the moon is

the same.

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 in meters per second per second is

zero

A 1-kg mass at the Earth's surface weighs

9.8 N

A rock is thrown vertically into the air. At the top of its path, its acceleration in meters per second per second is

9.8.

The mass of a pet turtle that weighs 10 N is

about 1 kg.

Which has the greater mass?

an automobile battery

A kilogram is a measure of an object's

mass.

A feather and a coin will have equal accelerations when falling in a vacuum because

the ratio of each object's weight to its mass 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 10-N falling object encounters 10 N of air resistance. The net force on the object is

0 N.

A skydiver jumps from a high-flying plane. As her velocity of fall increases, her acceleration

decreases

An apple weighs 1 N. When held at rest above your head, the net force on the apple is

0 N.

A falling skydiver of mass 100 kg experiences 500 N of air resistance. The acceleration of the skydiver is

0.5 g

Hang from a pair of gym rings and the upward support forces of the rings will always

add up to equal your weight

The newton is a unit of

force.

A skydiver steps from a helicopter and falls for a few seconds until he reaches his terminal velocity. Thereafter, until he opens his parachute, his acceleration

is zero

Whenever the net force on an object is zero, its 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

If one object has twice as much mass as another object, it also has twice as much

inertia.

A push on a 1-kg brick accelerates it. Neglecting friction, to equally accelerate a 10-kg brick, one would have to push with

10 times as much force.

A tow truck exerts a force of 3000 N on a car, accelerating it at 2 meters per second per second. What is the mass of the car

1500 kg

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 from the first force. The particle with both forces acting on it

continues at the speed it had when it encountered the second force

An object is propelled along a straight-line path in space by a force. If the mass of the object somehow becomes twice as much, its acceleration

halves.

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.

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 in meters per second per second is

1

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.

A 10-N block and a 1-N block lie on a horizontal frictionless table. To provide them with equal horizontal acceleration, we would have to push with

10 times as much force on the heavier block.

An object released from rest on another planet requires one second to fall a distance of 6 meters. What is the acceleration in meters per second per second due to gravity on this planet?

12

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 in meters per second per second of the car?

220

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

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

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

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

A skydiver, who weighs 500 N, reaches terminal velocity of 90 km/h. The air resistance on the diver is then

500 N

A 10-N falling object encounters 4 N of air resistance. The net force on the object is

6 N.

A 1-kg rock that weighs 9.8 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

9.8 N.

The human body can, under certain conditions, withstand an acceleration of 10 g. What net force would produce this acceleration of a 50-kg person

about 5000 N

If the mass of an object does not change, a constant net force on the object produces constant

acceleration.

Neglecting friction, a large block of ice and a small block of ice start sliding down an incline together. The heavier block will get to the bottom

at the same time as the light block.

A large and a small person wish to parachute at equal terminal velocities. The larger person will have to

get a larger parachute

A coconut and a feather fall from a tree through the air to the ground below. The amount of air-resistance force is

greater on the coconut

An object following a straight-line path at constant speed

has zero acceleration.

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 a non-rotating object has no acceleration, then we can say for certain that it is

in mechanical equilibrium

A heavy block at rest is suspended by a vertical rope. When the block is accelerated upward by the rope, the rope tension

increases.

If an object's mass is decreasing while a constant force is applied to the object, the acceleration

increases.

A lightweight feather slides off a table and falls through the air until it reaches the floor. During the time of its fall, its acceleration

is sometimes zero.

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

lead-filled ball

A ball thrown straight upward takes 10 seconds to go up and return to the ground. Because of air resistance, the time taken for the ball just to go up is

less than 5 s

A force is a vector quantity because it has both

magnitude and direction.

In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the

moon.

A ball is thrown vertically into the air. Because of air resistance, its time coming down compared to its time going up is

more

An object's weight may properly be expressed in units of

newtons.

Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has the same

none of these

The maximum acceleration of a car while towing a second car twice its mass, compared to its acceleration with no car in tow, is

one third.

Two factors that greatly affect air resistance on falling objects are the

size and speed of the object.

Your weight is

the gravitational attraction force between you and the Earth.

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

Strange as it may seem, it is just as hard to accelerate a car on a level surface on the moon as it is here on the Earth. This is because

the mass of the car is independent of gravity.

A rocket becomes progressively easier to accelerate as it travels upward from the ground mainly because

the mass of the rocket decreases as fuel is burned.

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

A rock weighs 30 N on Earth. A second rock weighs 30 N on the moon. Which of the two rocks has the greater mass?

the one on the moon

An object is propelled along a straight-line path by a force. If the net force were doubled, the object's acceleration would be

twice as much.

The force required to maintain an object at a constant velocity in free space is equal to

zero.