Power&Efficiency
A battery has 3V and 2A written on it, so what is the power?
P = 6W
what is the formula of Epot and Ekin?
Epot = m * g * h
Ekin = m * v2 * 1/2
What is the unit of force?
[F] = 1N
What is one difference between parallel and series circuits?
1. in a series circuit all the resistors are connected
2. in a series circuit the voltage splits
3. in a parallel circuit the current splits
What are some factors that affect resistance?
1. diameter
2. length
3. material
4. temperature
What are the units that power and efficiency are measured in?
[P] = 1W
[η] = 1 (%)
If an object rises by 66m, and it has a mass of 7kg, and g = 10 n/kg, what is the total potential energy?
unknown, because we do not know where 0 is
What is the definition of force?
F = m x a
what are the 3 necessities of a circuit? name one example
1. voltage source, ex: batteries, power supply
2. resistor, ex: lightbulb, fan
3. closed conductive path, ex: cables
What is the golden rule of mechanics?
what you do not do in force, you must do in distance
If a machine is supplied with 500J, yet it only uses 475.62J, what is its efficiency?
η=95.124%
A car drives up from 70m/s, and it has a mass of 99g, so what is its kinetic energy?
Ekin = 34.65
If 400J of work are done, and the distance travelled was 4 m, what was the force applied?
F = 100N
What can cause a short circuit?
the connection of the positive and negative terminal without the usage of any resistors
Describe an example of the law of conservation of energy
Ex: when a box falls, the kinetic energy increases as the gr. p. e. decreases, of which it previously had 100% of, then right before it hits the ground the kinetic energy is 100% and when the box hits the ground the energy all gets transformed into thermal energy
If I supply a lever, which has an efficiency of 64.85 %, with 1kj, what will the outcome energy be?
E = 648.5J
If an object rises by 500m, and it has a mass of 7kg, and g = 10 n/kg, what is the change of potential energy?
Epot = 35KJ
How much force will have to be applied to travel 8099m and use only 10000J of energy?
F = 1.23N
how is voltage and current measured?
U is measured in a parallel circuit with a voltmeter
I is measured in a series circuit with an ammeter
What does an energy flow diagram represent?
energy being transformed, in a visual and accurate way
If a lever has an outcome of 5082J, and the total efficiency is 47%, what was the income energy?
E = 10812.7J
If I apply 40N of force, and go 6 meters to travel up a hill, but I then decide to go up another 12 meters but this time I will use a lose pulley, how much work will I have done total?
W = 480J
Which of Newton's laws is "F = m x a"
It is the second law of motion
Compare current to a water circuit, and how it is measured in a series circuit.
The electrons are like the water, them flowing is a representation of current. In a parallel circuit we see the paths split, thereby splitting the water representing current. But in a series circuit, the path never splits, and the water stays together. Because you need to measure all electrons over a time interval to get the true results, and as shown a parallel circuit splits such electrons, current is measured in a series circuit.
What is Newton's 3rd law of motion?
if object a applies force to object b, object b applies force to object a