Work
Work is a measure of _______
How much energy is transfered
Directly
The standard unit for Work is a _____
Joule
How much energy does a 1500 W microwave use if it is on for 40 seconds?
60,000 J
During a physics lab, Jack and Jill ran up a hill. Jack is twice as massive as Jill, but Jill reaches the top of the hill in half the time.
1. Who did the most work?
2. Who did the most power?
Jack did the most work
Jack and Jill both generated the same power
If a car slams on the brakes, did the brakes do positive, negative, or zero work on the car?
Negative!
(Force of friction is in opposite direction of the car's displacement)
Which uses more power, a student that runs up the stairs or a student that walks? Assume they have the same mass.
The student that runs
The standard unit for Power is a ______
Watt
How powerful is a weight lifter who lifts a 400N weight 2 m in 1.6 seconds?
500 W
A student is walking forward with books in their backpack. What is the WORK the student is doing on the books?
Zero!
(Force is not parallel to displacement)
Which of the following is not a definition of power?
A.The rate of energy transfer
B. How many Joules are converted to other forms of energy
C. How quickly energy is converted
B - How many Joules are converted to other forms of energy
A Joule per second (J/s) is the same thing as a ______.
Watt
A weight-lifter is holding a barbell above his head. The barbell is 60 kg and is being held at a height of 1.9 m. How much work is the weight-lifter doing?
0 Joules
If the power an object has triples what will happen to its speed
it will triple
What are TWO other ways to say "JOULES"?
AKA, what combination of other units would be the same things as joules?
N*m
kg*m^2/s^2
A rocket is moving with a velocity of 500 m/s. If the power required to maintain this velocity is 10,000 W, determine the force exerted by the rocket.
20 Newtons
Braylen and Caleb are neighbors. Their yards are the same exact size. If it takes Braylen twice as long to mow his lawn compared to how long it takes Caleb, who did more work?
They did the same work
You push a box across the floor.
If the distance the box is pushed is doubled, AND the time it takes to do the work is cut in half, what happens to the power?
4 times greater
What are TWO other ways to say WATTS?
AKA, what combination of other units would be the same thing as watts?
N*m/s
kg*m^2/s^3
A 175 kW snow plow pushes a pile of snow a distance of 4.0 m in 8 seconds. What was the force applied to the snow?
350,000 Newtons