Energy by virtue of an object's position is called ____________________.
potential energy
100
What is the formula for impulse?
impulse = force x time
100
T or F If an internal net force acts on a system, the total momentum of the system will change.
False. An external force is needed.
100
Where does a roller coaster have the most kinetic energy?
At the bottom
200
The rate at which work is done is called ____________.
Power
200
Energy by virtue of an object's motion is called ______________________.
Kinetic energy
200
How are momentum and impulse related?
Impulse is equal to the change in momentum.
200
If a bullet is fired from a gun, how does the change in momentum of the bullet compare to the change in momentum of the gun?
They are the same.
200
If a roller coaster has 200 J of kinetic energy at the bottom of the track, how much potential energy will it have at the top of the track?
200 J
300
DOUBLE JEOPARDY!!!!
If you push an object with twice as much force three times as far, how much more work are you doing?
6 times more work
300
How much potential energy does a 7 kg box have that is on top of a table that is 3 m high?
PE = mgh = 7 kg x 10 m/s2 x 3 m = 210 J
300
Why is it beneficial for a cannon to have a long barrel?
A longer barrel increases the time over which the force of the cannon is exerted on the cannon ball and thus increases the impulse and change in momentum.
300
If a stretched rubber band has 40 J of potential energy, how much kinetic energy will it have after it is released?
40 J
300
DOUBLE JEOPARDY!!!
Are machine ever 100% efficient? Explain.
No, energy is also lost to friction and heat.
400
If you lift a 3 kg dumb bell 3 m, how much work are you doing?
W=Fd; F=w; w=mg; w=3kg x 10 m/s2=30 N
W=30 N x 3 m = 90 J
400
How much kinetic energy does a 400 kg car have if it is traveling at 6 m/s?
KE = 1/2mv2 = 1/2 x 400 kg x (6 m/s)2 = 1200 J
400
Explain how bouncing effects impulse.
Bouncing increases the impulse.
400
DOUBLE JEOPARDY!!!
A 50 kg astronaut floating in outer space throws a 10 kg backpack. If the backpack moves at a velocity of 15 m/s, what velocity will the astronaut move at?
50 kg * v = 10 kg * 15 m/s = 3 m/s
400
What is the mechanical advantage of a ramp that is 4 m high and 16 m long?
MA = input distance / output distance = 16 m / 4 m = 4
500
If you carry a 15 kg suitcase up a 10 m staircase in 25 s, what is your power?
P = W / t; W=Fd; F=weight; F=mg=15 kg x 10 m/s2=150 N; W= 150 N x 10 m = 1500 J
P = 1500 J / 25 s = 60 W
500
What will happen to a car's kinetic energy if its velocity is halved?
It will have 1/4 the kinetic energy
500
What is the average momentum of a 40 kg boy who runs 60 meters in 5 seconds?
p= mv = 40 kg x (60 m/5 s)= 480 kg*m/s
500
A 1000 kg train car moving at 15 m/s strikes a 500 kg stationary car. If they link together after the collision, what will their combined velocity be?
1000 kg * 15 m/s + 500 kg * 0 m/s = (1000 kg + 500 kg)*v
15000kg*m/s=1500 kg * v
10 m/s = v
500
What is the efficiency of a machine that produces 400 joules of useful work from 600 joules of input work?
Eff = output work / input work x 100% = 400 J / 600 J x 100% = 67%