Physics Chapter 9 Test
A car has 3000 J of kinetic energy then you double that car's speed, how much energy will it have then?
3000 = .5(6000)(1)^2, x= .5(6000)(2)^2 so x= 12000 J
How much work is done on a 20N crate that you lift 2 meters?
40J
How much power is expended if you lift a 60N crate 10 meters in one second?
600 Watts
An arrow and a bow has 70 joules of potential energy assuming no loss of energy to heat or friction how much kinetic energy will it have after it has been shot.?
70 joules
How many joules of work are done on a box with 25kg that is pushed 3 meters?
75 J
How much power is required to do 40 J of work in 5 seconds?
8 Watts
If the velocity of a moving object doubles that what else doubles? a. Acceleration b. kinetic energy c. momentum d. all of the above
All of the above
If you lift one load up two stories how much work do you do compared to lifting one load up one story
Doubled
If you lift two loads up one story how much work do you do compared to just lifting one load up one story
Doubled or twice
An object at rest may have one of the following energy, speed, velocity, or momentum
Energy
In physics work is defined as ______
Force (n) x distance (m)(measured in joules)
. How much farther from a car traveling at 100 km/s skid than the same car traveling at 50km/s?
Four times as far
If nelly newton pushes an object with twice(of the previous question) the work force twice the distance how much work will she do?
Four times more
As a pendulum swings back and forth ______
It's all potential energy at the two ends at the bottom and its kinetic at the middle and everything else is a combination
The unit of work is the _____
Joules
The ratio of output force to input force in a machine is what?
Mechanical advantage
An object with kinetic energy must be what?
Moving
Potential energy is the energy due to the objects _____
Position or location
Power is defined by ____
Power = Work divided by time (measured in Watts)
What has a greater kinetic energy a car moving at 30 kilometers per hour or a half as massive car moving at 60 kilometers per hour?
The car going 60 kilometer per hour
Which requires more work lifting 70kg 2 meters or 35kg 4 meters?
They require the same amount work
What is the unit of power _____
Watt
Energy is changed from one form to another with no net loss or game... sometimes true, always true, or never true
always true
If an object has kinetic energy then it must also have ____ a. Impulse b. force c. momentum d. acceleration
c. Momentum
A pulley system can change the.... a. direction of a force b. multiply the force c. increase the amount of work done d. both a and b e. both b and c
d. both a and b
A heavy object and a light object are released from rest at the same height and time in a vacuum as the fall they have equal what? A. energy b. Weight c. momentum d. all e. none
e. none
The ratio of useful work output to total work input is called what?
efficiency
The amount of potential energy possessed by an elevated object is equal to what?
mass times gravity times height(mgh) , or the work done to get it there
A job is done slowly and an identical job is done quickly both jobs require the same amount of work but different amounts of ____
power
When a car speed triples its kinetic energy does what?
x9
Kinetic energy is equal to what?.
½ x velocity squared x mass(.5mv^2