Energy and work Flashcards
What is energy?
Energy is the ability to do work.
It is also considered the ‘measurement’ of the ability to do work.
What is Kinetic energy?
Kinetic energy is a type of energy that is associated with the motion of an object.
Thermal energy?
Energy related to heat
List as many types of energy as you can
Thermal
Light
Gravitational Potential
Kinetic
Electrical
Chemical
What is the SI unit for energy?
The SI unit for energy is Joules
What is work? Define work.
‘work’ is the transfer of energy when an object is displaced by an external force
Work is also known as the transfer of mechanical energy.
What is the formula for work?
Work = Force x Displacement x cos theta
w = fs x cos(theta)
OR w=fs x cos(Theta) –> not scientifically correct
When is work done?
Work is done when force is applied to an object and thus results in displacement.
Work is also done when there is a change in energy
Is work a scalar or a vector quantity? Why?
Work is a scalar quantity as it deals with energy and the transfer of mechanical energy. Even though displacement is associated with work, it is not considered to be a vector quantity.
Energy is a scalar quantity and has no direction associated with it. Therefore, when calculating ‘work,’ the only thing that matters is the magnitude
What is the formula for kinetic energy?
1/2 x mass x velocity squared
What is the change in kinetic energy? This is also known as the net force of work
Change in kinetic energy is:
Final kinetic energy - Initial kinetic energy
What is gravitational potential energy?
Potential energy is defined as energy that is stored. Objects with potential energy have the ability to apply forces and do work.
In short, GPE is the energy possessed by an object due to its position in the gravitational field
What is the formula of gravitational potential energy?
GPE = Mass x Gravity (9.8) x Height
GPE = mgh
What is the conservation of energy?
The ‘conservation of energy’ states that energy is neither created nor destroyed. Energy is transferred from one form to another, whether it be from potential to kinetic or vice versa. This means that the mechanical energy is constant and therefore the same, before and after something has happened.
Define mechanical energy
Mechanical energy is defined as the energy associated with the position and motion of an object
Em (Initial) = Em (Final)
What is power?
Power is the measure of the rate at which work is done.
It is also known as the rate at which energy is transferred.
In short, power is the rate at which work is done or when energy is transferred
What is the formula for power?
The formula for power is: (note that ‘p’ is momentum and ‘P’ is Power)
Power = Work / Change in time
P = W/ t (triangle t meaning change in time)
It can also be found by:
Power = Force x Velocity
P = Fv
NOT P=MV
as P is MOMENTUM
What does the area underneath a force-distance time graph tell you?
It tells us the work done, since work is equivalent to force applied multiplied by the displacement
For the force-time graphs where it goes under the x-axis, how do you calculate the work done?
It will be the absolute value of the area, which represents the work done. Therefore, you will be adding the area underneath the x-axis instead of subtracting them as you would is displacement-time graphs and such
If there are multiple bodies in a system, then the work done will be different depending on how you look at it. For example, the amount of work done by the whole system can be zero, but the work done by individual components within that system can be different values other than zero.
True or False?
True
