Kinetic Energy
What is the energy called when a car is moving?
Kinetic Energy
What is potential energy?
Stored energy that depends on the position of an object
What’s the relationship between work and energy?
The amount of work done on an object is equal to the change in its kinetic energy.
What is mechanical energy?
Is the sum of an object’s kinetic energy and potential energy.
What does the Law of Conservation of energy state?
Energy can’t be created nor destroyed, it can only be transferred
Does the kinetic energy of an object depend on its velocity or acceleration?
Velocity.
TRUE or FALSE:
Gravitational Potential Energy is the only potential energy
False. One form of potential energy is GPE - Gravitational Potential Energy, there are other like Spring Potential Energy or Chemical Potential Energy
If you are rolling a ball with 3 joules of Energy on a flat surface how much Kinetic Energy does the ball have?
Also 3 Joules!
Name any 2 of the Energies (that we have talked about) that add up to make mechanical energy.
Kinetic Energy, Gravitational Potential Energy, Spring Energy, Work
Eating food before a workout is the conversion of chemical energy to what?
Mechanical Energy
What unit is kinetic energy measured in?
Joules (J)
What is the formula for Gravitational Potential Energy?
PE(g) = m * g * h
A boy lifts a box of apples that weighs 180 N. The box is lifted a height of 0.800 m. How much work did the boy do?
W=Fd
W = (180)(0.800)
W =144J
Is mechanical energy conserved in a roller coaster?
YES!
Where can you use the conservation of energy?
Laying in bed
Standing still
Starting and running in a race
Parked in a driveway and then backing up
All of them!!
What is the kinetic formula?
KE = 1/2 * m * v2
What is the formula for Spring Energy?
PE(s) = 1/2 * k * x2
How much work is being done by someone running 56m while he weighs 100kg?
54,936 J
A man is sitting on a 20 m height building and his mass is 50 kg. Calculate the mechanical energy?
The man is not moving, therefore, K. E = 0, The formula of mechanical energy M.E = 1/2 mv2 + mgh. Since K.E is 0, the equation becomes:
M.E = mgh
M.E = 50 ×9.81 ×20
M.E = 9810 J
What type of energy is visible with the human eye
Electromagnetic Energy
A farmer heaves a bale of hay with 7.56 kga final velocity of 4.75 m/s. What is the kinetic energy of the bale?
KE = 1/2 * m * v2
KE = (1/2) * (7.56 kg) * (4.75 m/s)2
KE = 85.3 J
How high will a 1.90kg stone go if thrown straight up by someone who does 75J of work on it?
PE = mgh and PE = W
75 = 1.90kg * 9.81 m/s2 * h
h = 75 / (1.90 * 9.81)
h = 4.02 m
Can work be negative? If so, what does it mean?
Yes, work can be negative, indicating that work is being done against a force, such as when slowing down an object. Negative work means that energy is being removed from the system.
How does friction affect the conservation of energy in mechanical systems?
Friction decreases the amount of mechanical energy in a system, since some of the energy is converted to heat.
Which of the following is a true statement about the conservation of energy?
a.Potential energy is always conserved.
b.Kinetic energy is always conserved.
c.Mechanical energy is always conserved.
d.Total energy is always conserved.
d.Total energy is always conserved.