Work/Power/Misc.
how are machines able to make work easier?
multiplying forces or changing their direction; total energy is conserved; but we can make work easier even if we aren't making it less
Energy is changed from one form to another with no net loss or gain, true or false
true
An arrow in a bow has 70 J of potential energy. Assuming no loss of energy due to heat, how much kinetic energy will it have after it has been shot?
70 J- conservation of energy
Potential energy is the energy an object has because of its _________
position/ location
an object has kinetic energy if.....
it is moving
How many joules of work are done on an object when a 25 N force pushes it 3.75 meters?
94 J
How would you define energy?
the ability to do work or cause change
A ball is thrown into the air with 278 J of kinetic energy which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is more than, less than, or equal to 278 J?
less than 278 J; energy not lost, just converted to other forms of energy due to air resistance (friction/heat)
The amount of gravitational potential energy possessed by an elevated object is equal to what?
its mass multiplied by the acceleration due to gravity multiplied by the height above the ground AND the work done to lift the object that distance
Types of energy include: (list at least 4 for full points)
potential, kinetic, mechanical, electrical, thermal, solar (radiant), sound, chemical, etc.
In physics, work is defined as..
force times distance
Kinetic energy of an object is equal to what?
one half the mass times the velocity squared
KE=1/2mv2
At which position does a falling object have 100 % Kinetic energy? (beginning, middle, end of the fall)
a falling object has the most kinetic energy right before it hits the ground
An elevated motionless pendulum has a potential energy of 5.3 J and a kinetic energy of 0 J. At a certain point after the pendulum is dropped it possesses 3.3 J of kinetic energy. Due to conservation of energy, how much potential energy would the pendulum posses at this point?
2 J of PE; 2 + 3.3 = 5.3 J which is what we started out with and we cannot destroy or create energy so we must have converted some of our potential energy to kinetic energy.
What is mechanical energy?
the sum of potential and kinetic energy
Describe the law of conservation of energy.
energy cannot be created or destroyed but can be transferred from one form to another
The energy an object has because it is above the earth's surface is called....
gravitational potential energy
Calculate the kinetic energy of a 6.00 kg object that is traveling at 2.50m/s.
18.8 J
At a certain point, a skater has a potential energy of 0 J and a kinetic energy of 22 J. When their kinetic energy is equal to 0 J, how much potential energy will they have?
22 J
What must be true of an object that possesses even a little bit of kinetic energy?
Describe a pendulum's motion using the terms kinetic and potential energy
at the end points of its swing (the highest points), its energy is all potential; at the lowest part of its wing, its energy is all kinetic; kinetic energy is converted into potential energy; potential energy is also converted into kinetic energy
Think back to your skate park simulation. Draw two points on a skate track where the skaters potential energies at either point would be equal and and the skaters kinetic energies would also be equal.
drawing should be at equal heights on opposite sides of a track. Potential energies would be equal as well as kinetic energies
Suppose a moving car has 1000 J of kinetic energy. If the car's speed doubles, how much kinetic energy would it then have?
4000 J
How much potential energy does a rock have when it is lifted by a force of 80 N for a distance of 12 m?
960 J; work required to lift the rock = potential energy it possess after it's been lifted
Calculate the kinetic energy of an 0.234 kg object with a velocity of 5.93 m/s.
4.11 J