Download 1. Compute the kinetic energy, in joules of a 1400-kg

1. Compute the kinetic energy, in joules of a 1400-kg automobile traveling at 40.0km/h. Also, by what factor does the kinetic
energy change if the speed is doubled?
2. Superman's mass is 1/4900 times the mass of a locomotive. How much faster than a speeding locomotive must he move to
have the same kinetic energy?
3. A 1.2kg cantaloupe is dropped (zero initial speed) from the roof of a 30m tall building. What is the kinetic energy of the
cantaloupe just before it strikes the ground?
4. A 15.0 kg bullet leaves the barrel of a gun at a speed of 240.0 m/s.
(a) Find the bullet’s kinetic energy,
(b) find the average force exerted on the bullet by the expanding gases as the bullet moves through the length of the
50.0 cm barrel.
5. A 625 kg roller coaster is moving at speed of 18.3 m/s. Determine the kinetic energy of a 625-kg roller coaster car that is
moving with a speed of 18.3 m/s.
b) The speed of the roller coaster car double. What is the kinetic energy of the of the roller coaster car?
c) What is the ratio of the kinetic energy?
d) Stopping distance is proportional to the amount kinetic energy. What would the ratio of the stopping distances
6. A bear with a mass of 218 kg runs up a hill. At the top of the hill, she has gained 23.5 kJ of potential energy. How high was
the hill?
7. A 2.5 kg ball hangs from the canopy over a wooden deck by a string that is 75 cm long. The height of the room is 3.0 m.
What is the potential energy of the ball
a) Relative to the deck?
b) Relative to the top of an 88 cm tall tabletop
c) Relative to the overhead canopy
8. A 2.45 kg rock is dropped from the top of a 15.5 m vertical cliff. What is the potential energy of the rock relative to the base of
the cliff before it is dropped?
9. A spring has a spring constant of k = 55.0 N/m. The spring is compressed a distance of 3.50 cm. What is the potential energy
stored in the spring?
10. A spring with a spring constant value of 125 N/m is compressed 12.2 cm by pushing on it with a 215 g block. When the
block is released, what velocity will the block have when it leaves the spring (we’re ignoring friction here)?
11. One way NASA determines how much fuel the space shuttle needs in order to reach high orbit is to calculate the change in
the gravitational potential energy the shuttle experiences from going to the surface of the Earth to high orbit.
a) Consider high orbit is 40 mile above the Earth’s surface how much energy is required? (mass of the shuttle is 2030 tons)
b) The mass density of rocket fuel is 12,200 watt hours per kilogram, how many kilograms of rocket fuel is needed
12. When considering construction of orbital satellites physics and engineers come up with a dollar per kilogram number to
determine the cost to put it in space. The number is partial based on the gravitational potential (not gravitational potential
energy)
a) Calculate the gravitational potential for high orbit.
b) Use the energy density of rocket fuel to determine the amount of rocket fuel needed to put 1kg in orbit
c) Rocket fuel is about $630 per gallon (which is 8 .66 pounds) how much will it cost to put one kilogram in high orbit.
13. There is a point between the Earth and moon were the gravitational forces are zero on an object, calculate the gravitational
potential and the gravitational potential energy of a 2030 ton object.
14. 5. One of the inventions dreamed up science fiction writers is what is called a space elevator, a “box” pulled up by a cable.
NASA predicted the cost to lift one kilogram in high orbit would by 100th the cost to use traditional methods, why?
15. One of the key components to a mass spectrometer is a voltage called “ the accelerating voltage”. Here is how it works; a
substance is vaporized, in the process of vaporizing all of the electrons are striped off. The gas is then moved into the
accelerating voltage. The accelerating voltage is basically two plates one positive and one negative, which push the substance to
one of the plates, where there is a hole where the substance will pass through.
a) Determine what plate is positive and which plate is negative if the arrow is the direction the substance is to move
b) The voltage between the two plates is 10V and vaporized carbon is placed between the plates, calculate the energy each
particle have in the voltage.
c) The electrostatic energy is transformed in to kinetic energy (1/2 mv^2) what is the difference in the kinematics energy of
carbon 12 and carbon 14?
d) What is the difference in the velocities of carbon 12 and carbon 14?
16. We need to construct a box of charge, and like all boxes of charge, it needs to be done one at a time, starting with the
corners. The instruction are written in a different language but the diagram has labeled each corner A,B,C and D. You presume
the box is assembled in alphabetical order. Charge A is 10 mC, charge B is 20 mC, charge C is -10 mC, and charge D is 10 mC.
D
B
10 cm
A
10 cm
C
a) How much work must be done to bring the first charge?
b) How much work must be done to bring in the third charge?
c) How much work must be done to bring in the last charge?
d) What is potential at the center of the square?
17.In an action-adventure movie, the hero lifts the 91-kg villain straight upward through a distance of 1.2 m in 0.51 s at a
constant speed. What power does the hero produce while doing this?
18. A person is making homemade ice cream. She exerts a force of magnitude 22 N on the free end of the crank handle, and this
end moves in a circular path of radius 0.28 m. The force is always applied parallel to the motion of the handle. If the handle is
turned once every 1.3 s, what is the average power being expended?
19.One Kilowatt hour (kWh) is the amount of work or energy generated when one kilowatt of power is supplied for a time of one
hour. A kilowatt hour is the unit of energy used by power companies when figuring your electric bill. Determine the number of
joules of energy in one kilowatt hour.
20. The cheetah is one of the fastest accelerating animals, for it can go from rest to 27 m/s (about 60 mi/h) in 4.0s. If its mass is
110 kg, determine the average power developed by the cheetah during the acceleration phase of its motion. Express your answer
in
a) watts
b) horsepower.
21. A 1900-kg car experiences a combined force of air resistance and friction that has the same magnitude whether the car goes
up or down a hill at 27 m/s. Going up a hill, the car's engine needs to produce 47 hp more power to sustain the constant velocity
than it does going down the same hill. At what angle is the hill inclined above the horizontal