Power, Work, Energy Laborator Flashcards
It is defined as the product of the net force acting on a body and the distance moved in the direction of the force.
work
work formula
w = (force)(distance)
SI unit for work
joules
joules is the unit of what vectors
(N)(m) or kg m^2/s^2
Only the component of the applied force (F) in the direction of motion of the lawn mower, ____, is used to do work on the lawn mower.
Fhorizontal
given that only Fhorizontal is used, the final formula for work is
W = Fdcosθ
An object is moved with a force of 15N across a horizontal surface. How much work is done if the object is moved 50m?
750 joules
650 J of work is done in moving a desk in a horizontal distance of 5m. How much force is used to move the desk?
130 N
It if the rate at which work is done
power
formula of power
W/t
SI unit for power
watts
watts is a combination of what vectors
joule/sec
A force of 150N is used to push a motorcycle 10m along a road in 20 sec. Calculate the power in watts.
W = (150N)(10m) = 1,500 Joules
P = W/t = 1,500 Joules / 20 sec = 75 watts
A pump lifts 20Kg of water in a vertical distance of 20m in each sec. What is the power output?
Take note: gravitational acceleration = 9.8 m/sec2
F = (20Kg)(9.8 m/sec2)
F = 196 N
W = (196N)(20m)
W = 3,920 joules
P = 3,920 joules / 1sec
P = 3,920 watts
It is the defined as the ability to do work.
energy
Two types of energy
kinetic
potential
energy in motion
kinetic enegy
energy that is stored
potential
SI unit of energy
Joules
KE is a scalar/vector quantity
scalar quantity
formula of kinetic enegy
1/2mv^2
What is the kinetic energy of a 60 Kg girl on skis traveling at 20 m/sec
KE = ½ mv2
KE = ½ (60Kg)(20 m/sec)2
KE = 0.5 (60)(400)
KE = 12,000 joules
A sports car is moving at 4.0 m/sec. if the mass of the car is 800 Kg, how much kinetic energy does it have?
Solution:
KE = ½ mv2
KE = ½ (800 Kg)(4 m/sec)2
KE = ½ (800)(16)
KE = 6,400 joules
is energy of position
gravitational potential energy
Potential energy formula
PE = mgh
A mass of 100 Kg is lifted a distance of 50m. How much potential energy does it possess?
PE = mgh
PE = (100Kg)( 9.8 m/sec2)(50m)
PE = 49,000 joules
The sum of kinetic energy and potential energy in a system is ___, in absence of friction.
constant
law of conservation of energy formula
KE + PE = constant
law of conservation of energy states
Energy cannot be created or destroyed; it may be transformed from one form to another, but the total amount of energy in a system remains constant.
rate at which work is done
power
amount of energy delivered when a force movesa an item
work
formula of force of spring
Fspring = (k)(x)
where K = spring constant x = distance
formula of potential energy of spring
PE = 1/2kx^2