Work Energy Power Flashcards
(21 cards)
What is the formular of kinetic energy
KE =
mass x velocity^2 x 1/2
What is the formular for work
W= force x distance
What is the formular for GPE
GPE = mass x gravitational field strength x height
A goat jump off a cliff. The goat has a mass of 50kg and the cliff is 450m high.
At what speed is the goat traveling at just when it hit the ground?
GPE = 450 X 50 X 10
GPE =225000 J
KE =GPE
KE = 225000J
as KE gained is GPE lost
KE=1/2 X mass x velocity^2
225000=1/2 x 50 x velocity^2
velocity=300m/s
How much does kinetic energy does a car store, traveling at 15 m/s with a mass of 1400kg?
KE= 1/2 X mass x velocity^2
KE =1/2 x 15^2 x 1400
KE= 157500 J
What is the conservation of energy
Energy is not created or destroyed, it is merely converted from one form to another
Describe the energy store/transfer of an apple pushed off a tree
Gravitational PE –> kinetic energy via mechanical transfer
Describe the energy store/transfer of a man pushing a shopping cart with food in it
Chemical –> kinetic via mechanical
Is convection a radiation form of transfer or is it thermal
thermal
Is conduction a radiation form of transfer or is it thermal
Thermal
How much work is done if you try to lift something too heavy that the object did not move at all
0 work has been done
What is the formular for hooke’s law
force = kx
What is k in hooke’s law
The spring constant
What does the hooke’s law actually show
-how much a spring will stretch if a certain force is applied
What does f=kx shows about the relationship between force and distance of which the spring is stretch
They are directly proportional
if the spring constant is low, how elastic is it?
-The lower the spring constant, the more elastic
A spring with an original length of 9cm and a spring constant of 5500N/m is loaded with a load of 280N. What is it’s final length?
14 cm
If there is a higher mass/force on a spring, will it stretch more or less
More
How would you measure the spring length
Using a ruler and calculating the difference between original length and stretched length
Read values at eye level
weight = force x ?
Acceleration of
Gravity towards the ground
What do you need to make sure every time you change the weight at a hooke’s law practical
The spring returns to its original position and remain as usual
