Vocab
What kind of energy depends on position?
GPE
What is required for something to have done work?
A force and a displacement
What has a greater impact on the KE of an object?
Doubling the mass or doubling the velocity?
Doubling the velocity
A pendulum swings from rest. The mass of the bob is 1 kg. It has 15 J of GPE. What is its speed at the bottom of the swing?
Approximately 5.5 m/s
When has an object experienced acceleration?
Change speed, change direction, or both
What kind of energy depends on how far it is compressed or stretched?
PEs
___________ is the rate at which work is done.
Power
What is the shape of a graph showing KE of an object vs the velocity of the object?
Increasing exponential
A pendulum swings. The mass of the bob is 1 kg. It has 15 J of KE. What is max height it can reach from the bottom of the swing?
Approximately 1.5 m
What kind of friction exists when an object is stationary? What kind of friction exists when an object is in motion?
Which coefficient of friction is always bigger (for the same object)?
Static Friction
Kinetic Friction
Static Friction
What kind of energy is the energy of motion?
KE
What develops more power:
A. 20 J of energy being used in 2 seconds
or
B. 10 J of energy being used in .5 seconds
B. 10 J of energy being used in .5 seconds
What is the relationship between GPE and KE for a swinging pendulum?
TE remains the same. KE increases as GPE decreases, then GPE increases as KE decreases.
A spring with a weight attached to it is hanging from the ceiling of a room. The weight is 20 N. The spring has a spring constant of 250 N/m. How far is the spring stretched?
.08 m
How do you calculate the strength of gravitational field?
g = Fg / m
N/kg = m/s2
Equal to finding acceleration due to gravity.
This kind of energy increases as an object experiences friction or air resistance.
Internal Energy
Is work done if a car is pushed on for 30 seconds with a force of 250 N but the car remains in place?
No, the object must be displaced
How could an object's kinetic energy change if its velocity remains constant and no outside forces interact with the object?
What is the total energy of this falling object?
Mass = 50 kg
H = 20 m
v = 12 m/s
13,400 J
When two objects collide and stick together, that is what type of collision?
What is the difference between momentum and impulse?
Momentum is the product of the mass and velocity of an object; impulse is the change in momentum.
This is the unit for energy.
Joule
Work, Energy, and Power are:
A. All vectors
B. Work & Energy are vectors, Power is a scalar
C. Work & Energy are scalars, Power is a vector
D. All are scalars
D. All are scalars
What is the change in kinetic energy of an object traveling initially at 5 m/s and increasing to 10 m/s, with a starting mass of 400 kg and an ending mass of 398 kg?
KEi = 5000 J
KEf= 19900 J
Change in KE = 14,900 J
What is the total energy of this falling object?
Mass = 50 kg
H = 20 m
v = 12 m/s
q = 6,600 J
20,000 J
An object is launched at a 32 degree angle to the x axis. It has an initial velocity of 14 m/s, ignore air resistance.
What is:
x component of v
y component of v
time in air
max height
final velocity in x direction
Vy = 7.42 m/s
Time = .76 s
Hmax = 2.81 m
Vxfinal = 11.9 m/s