Work/Energy Basic
What is the unit of energy?
Joules
What are the units of power?
Watt
PE + KE
This is the number that tells how many times a machine multiplies force.
mechanical advantage
Hooke's law describes the relationship between force and this quantity
stretch, length of displacement (deformation)
What is 1 Joule equate to?
1 N per meter
1kg per meter2 per second2
1 HP = 746 watts
What is the formula for potential energy?
PE= mgh
Name 3 of the 6 simple machines
The unit of spring constant (k)
Newtons/meter
Work a vector or scaler quantity?
scaler
A 200 N weight is lifted 2 m. How much work is done?
400 J
What is the formula for Kinetic Energy?
KE = 1/2mv2
An inclined plane is 5 m long and 2 m high. What is its ideal mechanical advantage?
2.5
What is the formula for efficiency of a machine?
Work out divided by Work in x 100
Give a conservative and nonconservative force?
conservative- gravity and spring force
A 5.2 kg object moves at 2.4 m/s. Find its kinetic energy.
15 J
Give a scenario where potential and kinetic energy change, but total mechanical energy stays constant.
roller coaster, trampoline, etc
Increasing the number of pulleys does this to the force needed.
decrease the effort force
A spring stretches 0.30 m with k = 120 N/m. Find the force
36 N
The work-energy theorem states that the change in kinetic energy equals this.
Work done on an object
A 0.01 kg bullet moves at 700 m/s. Calculate its kinetic energy.
2450 J
"Energy can neither be created nor destroyed" is in reference to what?
Law of conservation of energy
Efficiency of machines is less than 100%, why?
friction- thermal energy lost from system
A spring stretches 0.075 m with k = 600 N/m. Find the force
45 N