Momentum/Energy/Work
What does the Law of Conservation of Energy State?
Energy can not be created nor destroyed, only transformed
Where is the center of gravity of a uniform meter stick located?
At its center, 50cm
What is the difference between distance and displacement?
distance is a scalar quantity (magnitude)
displacement is a vector quantity (magnitude and direction)
Rotating in which direction is positive?
a) Clockwise
b) Counter-Clockwise
b) Counter-Clockwise
If the frequency of a system undergoing simple harmonic motion doubles, by what factor does the maximum value of acceleration change?
x4
Compare the kinetic energy of a 20,000-kg truck moving at 110 km/h with that of an 80.0-kg astronaut in orbit moving at 27,500 km/h.
KE(truck)= 9.34 x 106 J
KE(astronaut) = 2.33 x 109 J
A hammer is made of a heavy metal head and a light wooden handle. Where is the center of gravity located relative to the handle?
Closer to the metal head, because more mass is concentrated there.
A ball is thrown directly upward. At its peak, the acceleration is momentarily 0 m/s2. True or False.
False
Microwave ovens rotate at a rate of about 6 rev/min. What is this in revolutions per second? What is the angular velocity in radians per second?
0.1 rev/s
0.63 rad/s
If a pendulum makes 12 complete swings in 8.0 s, what are its (a) frequency and (b) period?
f = 1.5 Hz
T = 0.67 s
(a) Calculate the momentum of a 2000-kg elephant charging a hunter at a speed of 7.50m/s. (b) Compare the elephant’s momentum with the momentum of a 0.0400-kg tranquilizer dart fired at a speed of 600m/s. (c) What is the momentum of the 90.0-kg hunter running at 7.40m/s after missing the elephant?
a) 15000 kgm/s
b) 24 kgm/s
c) 666 kgm/s
Two point masses are placed on a number line:
Where is the center of gravity?
3 m
A ball is thrown directly upward. At its peak what is it's velocity and acceleration?
velocity = 0 m/s
acceleration = -9.8 m/s2
A baseball pitcher brings his arm forward during a pitch, rotating the forearm about the elbow. If the velocity of the ball in the pitcher’s hand is 35.0 m/s and the ball is 0.300 m from the elbow joint, what is the angular velocity of the forearm?
116.67 rad/s
A simple pendulum has a period T on Earth. If it were used on Planet X, where the acceleration due to
gravity is 3 times what it is on Earth, what would its period be?
T/(3)1/2
A car’s bumper is designed to withstand a 4.0-km/h (1.12-m/s) collision with an immovable object without damage to the body of the car. The bumper cushions the shock by absorbing the force over a distance. Calculate the magnitude of the average force on a bumper that collapses 0.200 m while bringing a 900-kg car to rest from an initial speed of 1.12 m/s.
F= -2822.4 N
A 10 m long, massless beam has:
Where should you place a support so the beam balances?
6 m from the left end
A speed boat travels 21 km at a constant speed. Assuming it traveled at 35m/s, how long was the speed boat traveling?
600 s
A fan blade is spinning at 10 rad/s when the power goes out. If the fan begins slowing down at an average rate of 1.5 rad/s2, how long will it take for it to stop?
6.67 s
What frequency is received by a mouse just before being dispatched by a hawk flying at it at 25.0 m/s and emitting a screech of frequency 3500 Hz? Take the speed of sound to be 331 m/s.
3785.95 Hz
A bullet is accelerated down the barrel of a gun by hot gases produced in the combustion of gun powder. What is the average force exerted on a 0.0300-kg bullet to accelerate it to a speed of 600.0 m/s in a time of 2.00 ms (milliseconds)?
9000N
An apple is dropped off of a building and falls for 7 seconds before hitting the ground.
What is the height of the building?
If the apple was instead thrown straight downward at a velocity of 1 m/s, how long would it fall before hitting the ground?
1) 240.1 m
2) 6.9 s
A watch is spun around in a loop on a chain. If we know that the tangential speed of the watch is 3 m/s and the angular velocity is 9 rad/s:
What is the length of the chain on the watch?
What is the centripetal acceleration of the watch?
1) 0.33 m
2) 27 m/s
(a) What frequency is received by a person watching an oncoming ambulance moving at 110 km/h and emitting a steady 800-Hz sound from its siren? The speed of sound on this day is 345 m/s. (b) What frequency does she receive after the ambulance has passed?
b) 734.9 Hz