Nine-to-Five
A teacher applies a force to a wall and becomes exhausted. Was work done?
No work done
Power is defined as the _______ is done.
(a) amount of work which
(b) direction at which work
(c) angle at which work
(d) rate at which work
(d) Power is the rate at which work is done
What is ALWAYS true for an object that possesses zero potential energy?
It must be on the ground.
What is the kinetic energy of a 3-kilogram ball that is rolling at 2 meters per second?
KE = 6 Joules
Give TWO acceptable units for work.
Joules
Newton*meters
kg*m^2 / s^2
Will lifts the 100-pound barbell over his head 10 times in one minute; May lifts the 100-pound barbell over her head 10 times in 10 seconds. Which student delivers the most power?
May
What is the potential energy of a 3 kilogram-ball that is on the ground?
0 Joules
What is the kinetic energy of a 2,000-kilogram boat moving at 5 m/sec?
KE = 25,000 Joules
A weightlifter lifts a 300-N barbell 3 meters above her head. Was Work done? If yes, how much?
Yes, 900 Nm
Name TWO acceptable units for power.
Watts
Joules / second
N*m / s
kg*m^2 / s^3
What is the potential energy of a 2-kilogram potted plant that is on a 1 meter-high plant stand?
20 Joules
When is the kinetic energy of a pendulum at its greatest?
(a) at the top of its swing
(b) at the bottom of its swing
(c) somewhere inbetween
(a) at the top of its swing
An impulse is a force acting over some amount of time to cause a change in momentum. On the other hand, work is a ______________ acting over some amount of ___________________ to cause a change in __________________.
force, time, energy
What is the meaning of a single unit of horsepower [hp]?
Ye-olde horse can lift a 75-kg object by a height of 1 meter in about 1 second.
Determine the amount of potential energy of a 5-Newton book that is lifted from the ground to a shelf that is 1.5 meters high.
GPE = 7.5 Joules
A 1-kilogram ball is thrown into the air with an initial velocity of 30 m/sec. How much potential energy does it have at the top of its arc?
GPE = KE = 450 Joules
You caught a fancy fancy vase as it fell off the counter, slowing its fall before it hit the ground. Did you do positive, negative, or zero work on the vase?
Negative work
On a recent adventure trip, Anita Break went rock-climbing. Anita was able to steadily lift her 80.0- kg body 20.0 meters in 100 seconds. Determine Anita 's power rating during this portion of the climb.
Power = 160 Watts
The potential energy of an apple is 6.00 joules. The apple is 3.00-meters high. What is the mass of the apple?
mass = 0.2 kg
A toy car is moving along with 0.40 joules of kinetic energy. If its speed is doubled, then its new kinetic energy will be _______.
Quadrupled, 1.6 Joules