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