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P1 Conservation and Dissipation of Energy
1.
What term is used to describe an object or group of objects in physics?
a) machine
b) surroundings
c) store
d) system
2.
What term is used to mean everything outside of a system?
a) surroundings
b) outliers
c) outsiders
d) waste
3.
What change happens to the energy store of the system when a ball is projected upwards?
a) kinetic to mechanical
b) gravitational potential to kinetic
c) kinetic to elastic potential
d) kinetic to gravitational potential
4.
What change happens to the energy store of the system when an object hits an obstacle?
a) kinetic to gravitational potential
b) kinetic to heat
c) kinetic to elastic potential
d) kinetic to gravitational potential
5.
In which of the situations is mechanical work done to increase a kinetic energy store?
a) All three other answers
b) an object being accelerated by a constant force
c) an object falling under gravity
d) a car pulling away at the start of a race
6.
What energy change happens to the system when a vehicle brakes and slows down?
a) kinetic to thermal
b) kinetic to elastic potential
c) none as the total energy remains constant
d) heat to thermal
7.
In which of the following systems is electrical energy transferred mainly to the thermal energy of water?
a) electric blanket
b) electric kettle
c) electric toaster
d) fridge
8.
What does the term closed system mean in physics? A system where…….
a) the total energy does not change
b) the object is not available to do work
c) a system where the lid is on to keep heat in
d) a system where all the doors are shut
9.
What can you say about the energy input and output of a closed system?
a) they are equal
b) the output is zero
c) the input is zero
d) they are both zero
10.
What term is used to describe energy that has spread out into a less useful form?
a) disrupted
b) dissipated
c) dissolved
d) discredited
11.
What phrase is used to refer to the fact that energy cannot be created or destroyed?
a) the energy creation rule
b) the energy transfer convention
c) the second law of thermodynamics
d) the conservation of energy
12.
What term is used to describe energy that is dissipated and no longer useful?
a) transferred
b) wasted
c) thermal
d) heat
13.
Which of these could be described as a closed system?
a) a frictionless pendulum
b) a cup of tea
c) a running cat
d) a falling raindrop
14.
The initial energy of a closed system is 120 J. Which of the following could be its energy some time later?
a) 130 J
b) 120 J
c) 110 J
d) All three other answers
15.
What is the main reason real mechanical systems are not closed?
a) conservation of energy
b) friction
c) conduction of heat
d) poor construction
16.
Which of the following words is defined as, the energy transferred when a force moves an object through a distance?
a) thrust
b) drag
c) power
d) work
17.
What is the unit is used for energy in physics?
a) Watt, W
b) Joule, J
c) Newton, N
d) kilogram, kg
18.
Which of the following is measured in joules?
a) power
b) work
c) force
d) momentum
19.
What is the unit is used for force in physics?
a) Watt, W
b) Newton, N
c) Joule, J
d) meter, m
20.
What term is used in physics to mean distance in a particular direction?
a) directional distance
b) replacement
c) vector distance
d) displacement
21.
Which of the following gives the correct equation to calculate the work done, W, when a force F moves an object over a displacement of s meters?
a) W = F/s
b) W = s/F
c) W = Fs
d) W = Fs
2
22.
How much work is done when a force of 1 N moves an object 1 m?
a) 1 W
b) 1 N
c) 2 N
d) 1 J
23.
Calculate the work done when a force of 5 N is used to push a box 3 m?
a) 15 J
b) 8 J
c) 2 J
d) 35 J
24.
How far could a force of 3N pull a wooden block before transferring 12 J of energy?
a) 40 cm
b) 36 m
c) 3.6 m
d) 4 m
25.
20 J of work was done as a shopping trolley was pushed 5 m. Calculate the force used to push the trolley.
a) 4 N
b) 100 N
c) 0.25 N
d) 25 N
26.
Which of the following best describes the energy transfer caused by friction
a) frictional forces cause the objects to heat up
b) work done against friction transfers energy to a thermal store
c) friction works against the motion to generate heat
d) friction causes rubbing which creates thermal energy
27.
Which of the following is the symbol and unit used for gravitational potential energy?
a) E
p
/ J
b) E
p
/ N
c) E
g
/ J
d) E
g
/ N
28.
Which of the following is the symbol and unit used for gravitational field strength?
a) g / J/kg
b) g / N/g
c) g / N/kg
d) f / N/g
29.
Which of the following is the symbol and standard unit used for mass?
a) m / g
b) m / lb
c) m / T
d) m / kg
30.
Which of the following is the equation used to calculate gravitational potential energy gained by an object that is lifted through a height h?
a) E
p
= m g / h
b) E
p
= m / g h
c) E
p
= m g h
d) E
p
= m g h
2
31.
Calculate the energy gained when a 2 kg mass is lifted by 3 m. g = 10 N/kg
a) 6 J
b) 600 J
c) 60 J
d) 0.6 J
32.
Calculate the energy gained when a 3 kg mass is lifted by 2 m. g = 10 N/kg
a) 6 J
b) 60 J
c) 600 J
d) 0.6 J
33.
On the Jupiter, g = 25 N/kg Calculate the energy gained when a 2 kg mass is lifted by 2 m.
a) 10 J
b) 100 J
c) 50 J
d) 500 J
34.
Which of the following is the correct rearrangement of the equation for gravitational potential energy that has h as the subject?
a) h = m E
p
/ g
b) h = gE
p
/ m
c) h = m g E
p
d) h = E
p
/ m g
35.
Calculate the height that 100 J of work could lift a 2 kg cat. g = 10 N/kg
a) 500 m
b) 2 m
c) 5 m
d) 200 m
36.
Which of the following is the symbol and unit used for kinetic energy?
a) E
m
/ J
b) E
k
/ N
c) E
k
/ J
d) E
v
/ W
37.
What symbol is commonly used for speed and velocity in physics?
a) s
b) d
c) D
d) v
38.
What is the standard unit of speed and velocity used in physics calculations?
a) s/m
b) mph
c) m/s
2
d) m/s
39.
Which of the following equations can be used to calculate the kinetic energy of an object of mass m travelling at a speed v?
a) all of them
b) E
k
= ½ m v
2
c) E
k
= m v
2
/ 2
d) E
k
= 0.5 m v
2
40.
Calculate the kinetic energy of a 2 kg cat running at 2 m/s.
a) 8 J
b) 2 J
c) 4 J
d) 16 J
41.
Calculate the kinetic energy of a 1 kg kitten running at 4 m/s.
a) 4 J
b) 2 J
c) 8 J
d) 16 J
42.
Calculate the kinetic energy of a 4 kg cat running at 4 m/s.
a) 32 J
b) 64 J
c) 16 J
d) 8 J
43.
Which of the following is the correct rearrangement of the equation for kinetic energy that has v as the subject?
a) v = 2 E
k
/ √m
b) v = 2 √(E
k
/ m)
c) v = √(E
k
/ 2m)
d) v = √(2 E
k
/ m)
44.
Calculate the speed of a 4 kg cat running with a kinetic energy of 32 J
a) 2m/s
b) 4 m/s
c) 16 m/s
d) 8 m/s
45.
Calculate the speed of a 2 kg cat running with a kinetic energy of 100 J
a) 10 m/s
b) 50 m/s
c) 5 m/s
d) 20 m/s
46.
Which of the following is the symbol and unit used for elastic potential energy?
a) E
e
/ J
b) E
e
/ N
c) Pe / J
d) E
e
/ W
47.
In the equation for elastic potential energy what does the symbol k represent?
a) spring constant
b) kinetic energy
c) elastic coefficient
d) length of spring
48.
What are the standard units used to measure spring constant?
a) Nm
b) N/m
2
c) N/m
d) J/m
49.
What force would be required to extend a length of elastic of spring constant 5 N/m by 2 m?
a) 2.5 N
b) 20 N
c) 10 N
d) 5 N
50.
What force would be required to extend a length of elastic of spring constant 2 N/m by 4 m?
a) 2 N
b) 8 N
c) 16 N
d) 4 N
51.
Which of the following gives the equation used to calculate the energy transferred to a spring of spring constant k N/m as it is extended by a length e meters?
a) E
e
= 2 k e
2
b) E
e
= ½ k e
2
c) E
e
= e k
2
d) E
e
= ½ ek
2
52.
Calculate the energy transferred to a spring of spring constant 4 N/m as it is extended by 2 m.
a) 2 J
b) 8 J
c) 4 J
d) 16 J
53.
Calculate the energy transferred to a spring of spring constant 2 N/m as it is extended by 4 m.
a) 2 J
b) 4 J
c) 8 J
d) 16 J
54.
Calculate the energy transferred to a spring of spring constant 40 N/m as it is extended by 0.5 m.
a) 50 J
b) 0.5 J
c) 20 J
d) 5 J
55.
Which of the following is a standard method of reducing the energy wasted by frictional forces in a system?
a) thermal insulation
b) double glazing
c) electrical insulation
d) lubrication
56.
Which of the following is a standard method of reducing the heat energy wasted through conduction and convection in a system?
a) lubrication
b) thermal insulation
c) electrical insulation
d) construction from metal
57.
Which of the following would increase the efficiency of an electric kettle?
a) use a lower voltage so it takes longer to boil
b) half fill the kettle with water each time and boil it twice
c) make the kettle form a material that has a higher thermal conductivity
d) make the kettle form a material that has a lower thermal conductivity
58.
Which of the following would increase the efficiency of an electric motor?
a) use a motor with wires that don’t conduct electricity as well so they stay hot
b) insulate the motor with a low thermal conductivity material
c) all of the other three
d) make the motor spin freely on its bearings by oiling
59.
Which of the following is the equation used to calculate efficiency?
a) efficiency = useful input energy / total output energy
b) efficiency = useful output energy x total input energy
c) efficiency = useful output energy / total input energy
d) efficiency = wasted output energy / total input energy
60.
Calculate the efficiency of a lightbulb that emits 6 J of light energy for every 12 J of electrical energy input.
a) 1
b) 2
c) 0.5
d) 4
61.
Calculate the efficiency of a lightbulb that emits 12 J of light energy for every 12 J of electrical energy input.
a) 2
b) 4
c) 12
d) 1
62.
Calculate the percentage efficiency of a lightbulb that emits 2 J of light energy for every 10 J of electrical energy input.
a) 0.2
b) 0.02
c) 0.08
d) 0.8
63.
Calculate the light energy emitted by a bulb with an efficiency of 0.8 from an electrical energy input of 1000 J
a) 80 J
b) 200 J
c) 800 J
d) 1250 J
64.
Calculate the waste energy emitted by a bulb with an efficiency of 0.6 from an electrical energy input of 100 J
a) 60 J
b) 40 J
c) 140 J
d) 6 J
65.
Which of the following is the definition of power in physics?
a) rate of energy transfer
b) amount of energy transfer
c) efficiency of energy transfer
d) velocity of energy transfer
66.
Which of the following is also a definition of power in physics?
a) amount of work done
b) rate of work done
c) efficiency of work done
d) velocity of work done
67.
What is the symbol and standard unit for power?
a) P / Joules
b) V / Volts
c) P / Watts
d) P / kWh
68.
Which of the following is the same as 1 W ?
a) 1 N/J
b) 1 J/s
c) 1 J/m
d) 1 J/W
69.
Two electric motors are used to lift the same object by the same height. Which of the following statements is not true.
a) The more powerful motor uses and transfers more energy.
b) The more powerful motor lifts the mass in a shorter time.
c) The more powerful motor will use electrical energy at a higher rate.
d) The less powerful motor takes longer to use the same amount of energy.
70.
Which of the following is the equation that can be used to calculate the power of a system from the energy transferred and the time taken.
a) P = E x t
b) P = t / E
c) P = Et
2
d) P = E / t
71.
Calculate the power of a motor that transfers 20 J in 5 s
a) 100 W
b) 0.25 W
c) 4 W
d) 25 W
72.
Calculate the power of a motor that transfers 200 J in 10 s
a) 20 W
b) 2000 W
c) 200 W
d) 0.02 W
73.
Calculate the energy transferred by a 60 W light bulb in 2 s
a) 12 J
b) 30 J
c) 0.03 J
d) 120 J
74.
Calculate the energy transferred by a 100 W TV in 1 min
a) 100 J
b) 60 J
c) 6 kJ
d) 1000 J
75.
Calculate the time that a battery with a store of 8000 J battery can run a 2 W LED bulb.
a) 4000 s
b) 16000 s
c) 2s
d) 2000s
76.
Calculate the time that a battery with a store of 8000 J battery can run an 8 W LED bulb.
a) 100 s
b) 1000 s
c) 10 s
d) 1 s
77.
Calculate the power required to lift a 5kg cat at a rate of 5 m/s g = 10 N/kg
a) 25 W
b) 2500 W
c) 250 W
d) 2.5 W
78.
Calculate the power required to accelerate a 5 kg rocket to 100 m/s in 2s
a) 250 W
b) 25 kW
c) 2.5 kW
d) 250 kW
79.
Calculate the power needed to stretch a bungee cord of spring constant 100 N/m by a length of 10 m in 4 seconds.
a) 1350 W
b) 1250 W
c) 1450 W
d) 1150 W
80.
Calculate the efficiency of a 120 W light bulb that transfers 72 W of waste thermal energy.
a) 0.6
b) 1.7
c) 0.72
d) 0.4
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