exercise 2 questions #75

Speed

A measure of how fast something is moving.

Velocity

The property which specifies the speed and direction of motion an object.

8m/s

The speed of an athlete who covers a distance of 80 meters in 10 seconds.

240 km

The distance a car would travel in 3 hours if it moved at an average speed of 80km/hr.

Inertia

The property of things to resist changes in state of motion.

Weight

The force due to gravity.

Mass

A kilogram is a measure of an object's mass.

Volume

Space occupied by a given mass.

Friction

The resistive force that opposes motion or attempted motion of an object.

Support force

The force that supports an object against gravity, often called the normal force.

Acceleration

The rate of change of velocity with time.

Free fall

A state of fall under the influence of gravity, free from air resistance.

Both of these

Compared with a 1kg block of solid iron, a 2kg block of solid iron has twice as much mass and weight.

Force

Simply stated as push or pull.

The gravitational attraction between you and the Earth

Your weight.

Gravitational acceleration

One object that has twice as much mass as another object also has as much gravitational acceleration.

The Same

Compared with the same mass of a certain object on Earth, the mass of the same object on the Moon is the same.

10 N (newtons)

A 1kg mass at the Earth's surface weighs about 10 N.

5N

The magnitude of the net force on the object pulled northward with a force of 10N and southward with a force of 15N.

Is also zero

Whenever the net force of an object is zero, its acceleration is also zero.

Read half of your weight

When you stand at rest on a pair of bathroom scales, the reading on the scales will always read half of your weight.

100 N

The reading on each scale when a man weighing 200N stands at rest on two bathroom scales so that his weight is distributed evenly.

10N

The force of friction on a sliding object.

All of these

The resistive force of friction occurs for all surfaces.

Both of these

The amount of friction that occurs when two material surfaces slide against each other depends on both the materials and their texture.

20km/hr

The average speed of a horse that gallops a distance of 10km in a time of 30 minutes.

0

The acceleration of a car that maintains a constant velocity of 100km/hr.

Velocity increases

As an object freely falls, its velocity increases.

10m/s

The gain in speed each second for a freely falling object.

Free fall

Motion under the influence of gravitational pull only.

Terminal velocity

The speed at which the acceleration of a falling object terminates when air resistance balances its weight.

Mass

An object maintains its state of motion because it has mass.

Magnitude and direction

Force is a vector quantity because it has magnitude and direction.

10 times as much as

The force of gravity on a 10kg brick is 10 times as much as the force on a 1kg brick.

6m/s

A car accelerates from rest at 2m/s. Its speed 3 seconds after starting moving is 6m/s.

100m/s

Ten seconds after starting from rest, a freely falling object will have a speed of about 100m/s.

60m/s

If an object is in free fall for 6 seconds, its approximate speed exactly 6 seconds later is 60m/s.

Acceleration

Disregarding air resistance, objects fall at constant acceleration.

500m

The distance a freely falling object (g=10m/s2) will fall in 10 seconds is 500m.

6km/hr/s

If a car increases its velocity from zero to 60 km/hr in 10 seconds, its acceleration is 6km/hr/s.

Decreases

If an object's mass is increased while a constant force is applied, its acceleration decreases.

6N

The net force on a 10N falling object encountering 4N of air resistance is 6N.

0N

The net force on a 10N falling object encountering 10N air resistance is 0N.

1500Kg

The mass of a car if a tow truck exerts a force of 3000N, accelerating it at 2m/s2.

Acceleration

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

Zero

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

At the same time as the small block

In a vacuum, 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 small block.

500N

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

10 times as much force

To equally accelerate a 10kg brick, one would have to push a 1kg brick with 10 times as much force.

Zero

When a falling object reaches its terminal velocity, its acceleration is zero.

Neither

A falling object that has reached its terminal speed continues to gain neither speed nor acceleration.

1000N

The ball exerts a reaction force against the bat of 1000N when a baseball player bats a ball with a force of 1000N.

Pull of ball’s mass on earth

As a ball falls, the action force is the pull of the Earth's mass on the ball, and the reaction force is the pull of the ball’s mass on earth.

500N

A person is attracted toward the center of the Earth by a 500N gravitational force; the force of attraction of the Earth toward the person is 500N.

The person's body pulling on the Earth

The reaction to the gravitational force of a person's body toward the Earth is the person's body pulling on the Earth.

The same for both

A car traveling at 100km/hr strikes a bug; the force of impact is the same for both the car and the bug.

road

The force exerted on the tires of a car to directly accelerate it along the road is exerted by the road.

push you back

If you push an object, the object will push you back.

False

An object in motion comes to a stop without any external force is false.

False

The weight of a given object is the same on Earth and on the Moon is false.

True

The mass of a given object is the same on Earth and on the Moon is true.

False

Acceleration is the rate of change of distance per unit time is false.

False

The law of inertia holds true only for objects in motion, but not for those at rest is false.

True

The ratio of gravitational force to mass is the same for all objects in the same locality is true.

False

When acceleration is less than 'g', it is free fall is false.

True

Every object possesses inertia is true.

True

In the absence of friction, no force is required to keep a horizontally moving object moving is true.

False

Volume indicates how much mass an object contains is false.

True

Weight is a gravitational force exerted on an object is true.

False

Density is the amount of matter in a substance is false.

The higher becomes its inertia

The higher the mass of an object, the higher becomes its inertia.

True

In a vacuum, the acceleration of a free falling stone and feather is equal is true.

True

The weight of an object is higher on Earth than on the Moon is true.

True

Without net force there is no acceleration.