Ch. 11 and 12 physics

The brakes on a car exert a frictional force of 6000 N in getting the car to stop. if the work done by the brakes is 120 000 J in coming to a stop, how many meters did the car travel after the driver applied the brakes.

20 m

A first-class lever has the

fulcrum in the middle

Which object does not have momentum

A rock by the side of the road

An object weighing 75 N is dropped from the top of a building an falls a distance of 28 m to the ground. How much work does the gravity do on the object from the time it is dropped to the time it hits the ground?

2100 J

which of the following is an example of a wheel and axel

A screwdriver

When objects are moved further apart from each other, the force of gravity

Decreases

When that same force is applied to two different masses, these masses will have _______ accelerations

Different

The law that states that every object maintains constant velocity unless acted on by an unbalanced force is

Newton's first law of motion

The law that states that the unbalanced force acting on an object equals the objects mass times its acceleration is

Newton's second law of motion

Earth pulls in the moon and holds the moon in its orbit. The moon pulls on earth with an equal and opposite force. This is an example of

Newton's third law

The law that states that for every action force there is an equal and opposite reaction force is

Newton's third law of motion

Gravitational potential energy depends on the

all of the above (the mass of an object, the acceleration due to gravity, the height of the object)

A pendulum is swinging back and forth and has kinetic energy of 400 J at a particular point in its path. Which of the following statements is not true

both kinetic and potential energy are decreasing

A machine is a device that

can multiply and change the direction of an input force

An inclined plane

changes both the magnitude and the direction of the force.

The kind of energy associated with atomic bonds is

chemical energy

How many sig figs are in .003420

Four

which of the following statements about work and energy is not true

work and energy are always equal

what do you not need to calculate momentum

Acceleration

30 g to kg

.030

what is the mechanical advantage of a single fixed pulley

1

A medicine ball has a mass of 5 kg and is thrown with a speed if 2 m/s. What is the kinetic energy

10 J

A weightlifter presses a 400 N weight 0.5 m over his head in 2 seconds. What is the power of the weightlifter

100 watts

The efficiency of a ramp is 75%. If the amount of work input is 240 J, what is the amount of useful output.

180 J

A man pushes a create along a factory floor by exerting a force of 55 N. if the create moves a distance of 4.0 m, how much work does the man preform

220 N

What is 342000000 in scientific notation.

3.42 x10 to the 8

What is 0.0003452 in scuentific notation

3.452 x 10 to the -4

what is the gravitational potential energy of a 55 kg box that is 8.0 m above the ground

4300 J

What is the mechanical advantage of a ramp that is 10 meters long and 2 meters high

5

A 10.0 kg dog chasing a rabbit north at 6.0 m/s has a momentum of

60.0 kg m/s north

Convert 74km to meters

74000

The value for acceleration of objects in free fall near earth is _____

9.81 m/s 2

When throwing a dart at a target, you should always aim ______ the bull's eye

Above

According to Newton's second law of motion, force is the product of mass and __________.

Acceleration

What happens immediately after a skydiver opens her parachute

Air resistance greatly increases

What are the units of work

All of the above (J, N*M, kg*m2/a2)

What are the units of power

All of the above (watts, horsepower, joules per second)

If you are given a mass of an object in pounds, the time in seconds, and the distance in feet, what must you do before you can calculate the momentum in SI units

Convert the mass to kg and the distance to meters (both a and b)

A ______________ is defined as a machine made up of more than one simple machine.

Compound machine

How many sig figs are in 23000.

Five

the motion of an object resulting from only the force of gravity is _________.

Free fall

All levers have a rigid arm that turns around a point is called the ____________.

Fulcrum

What is the prefix for 10 to the 2

Hecto

The tendency of an object at rest to remain at rest, or if moving, to continue moving at a constant velocity is _________.

Inertia

What is the prefix for 10 to the 3

Kilo

The energy of a moving object due to its motion is called ________________.

Kinetic energy

An object with a small mass has ______ inertia than an object with a large mass

Less

What unit is used to measure acceleration in free fall

M/s2

If you divide momentum by velocity, the result is the value of the objects

Mass

Mass is a measure of the amount of ________ in an object

Matter

A quantity that measures how much a machine multiplies force or distance is called ______________.

Mechanical Advantage

The sum of the kinetic and potential energy of large-scale objects in a system is called

Mechanical Energy

What is the prefix for 10 to the 6

Mega

What is the prefix for 10 to the -3

Milli

Mass times velocity equals ________

Momentum

Whenever an object is standing still, the value(s) that is/are always zero is/are

Momentum, speed and velocity (all of the above)

The SI unit of force, named for the scientists who described the relationship between motion and force, is called tge

Newton

The stored energy resulting from the relative positions of objects in a system is called _____________

Potential energy

A quantity that measures the rate at which work is done is called _____________.

Power

A ____________ is an inclined plane wrapped around a cylinder

Screw

Newtons _________ law tells us how much an objects speed will be increased or decreased by an unbalanced force

Second

A wheelbarrow is an example of a

Second-class lever

If two objects with different masses and traveling with different velocities collided, what law allows you to predict the motion of the objects after they collide

The law of conservation of momentum

Weight is best described as

The downward force exerted on objects due to gravity

What is the unbalanced force that slows down a ball rolling across the floor

The force of friction.

What is the reaction force when you place a cup in a table

The force of the table on the cup

The greatest gravitational force would occur between

The moon and earth

Which statement about action-reaction forces is incorrect

They always act on the same object

In the absence of air resistance, how would the acceleration of a 1.5 kg book and the acceleration of a 15 kg rock differ if the objects were dropped from the same height

They would not differ; they would stay the same

Power is calculated by dividing work by__________.

Time

What is the equation for weufgt

W = mg

Horsepower is the common unit of power in rating engines. However, the official SI unit of power is the _________.

Watt

The mass of an object remains constant while its _________ varies according to the gravitational force it experiences

Weight

A boy pushes on a parked car with a force of 200 N. The car does not move. How much work does the boy do on the car?

Zero

When two Billard balls collide, the total change in momentum of the balls is ______

Zero

A pair of tweezers is

a compound machine made of two third-class levers

which of the following is an example of a third-class lever

a hand-held boat paddle

which of the following is a compound machine

a pair of pliers

which of the following is not a simple machine

a pair of scissors

which of the following processes requires the most work

a person lifts a 1 kg weight 1 m off the floor.

which of the following is not in; the inclined plane family

a wheel and axle

The ratio of useful work outpt to work input is measure of ______________.

efficiency

The law of conservation of energy states that

energy can neither be created nor destroyed.

which of the following is an example of mechanical energy

potential energy