Energy types/transfers
Name 3 forms/stores of energy
Teacher judgement
Describe kinetic energy
Energy in moving objects
Describe potential energy
Gravitational energy of a mass with a relative height
Describe Power
Energy per second
True or false:in a free fall, if the efficiency is 100%, the potential energy at the top height is the same as the kinetic energy before touching the ground
true
Which energy form is present in a banana?
Chemical
What is the equation of kinetic energy
1/2*m*v2
What is the equation of potential energy
m*g*h
What is the equation and unit of power?
P=Energy/time Watt
A rock of mass 30kg falls from a height of 40m, what is its kinetic energy near the ground
True or false: It is possible in real life to have an energy transfer with 100% efficiency
False
A car of mass 700kg moves at a speed of 30m/s, what is its kinetic energy?
A car of mass 700kg is being lifted on Mercury (g=3.7) at a height of 5m, what is the potential energy?
12950J
A car of mass 700kg accelerates to a speed of 25m/s in 6 seconds, what was the power of the engine?
36,46 KW
A ball of mass 3kg is thrown upwards at a speed of 6m/s and it reaches a height of 4m, what is the gravitational field strenght?
4,5
Describe the energy transfer in the following situation: A phone playing loud music while being plugged in a charger.
Electrical to chemical to sound
4000J of energy is transfered to a ball of mass 3kg with an efficiency of 85%, what is the speed of the ball?
47,6m/s
A rock of mass 30kg falls on Earth and gains a Kinetic energy of 9000J before touching the ground. If the efficiency of energy transfer was 100%, what was the height of the rock?
30m
A thermal power plant generates 50000J of useful energy in 10 seconds. At the same time, it wasted 130000J in the same 10 seconds. What is the efficiency of the power plant?
27,7%
A bouncing ball of mass 2kg falls on Earth from a height of 150m. If the efficiency of energy transfer was 80% during the free fall (because of air resistance), what is the power it can transmit to the ground if the contact time is 0,25 seconds?
9600W