Energy: kinetic and potential
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1.Which of the following is the correct definition of kinetic energy?
Easy- AEnergy stored in an object due to its position
- BEnergy of motion
- CEnergy released by chemical reactions
- DEnergy transferred by sound waves
2.What type of energy does a moving car mainly possess?
Easy- AGravitational potential energy
- BElastic potential energy
- CKinetic energy
- DThermal energy
3.Mechanical energy is the sum of kinetic energy and potential energy.
EasyTrue or false?
4.A ball is dropped from a height. At the moment it hits the ground, its energy is mostly:
Easy- AGravitational potential energy
- BKinetic energy
- CElastic potential energy
- DChemical energy
5.Which of the following are forms of potential energy? (Select all that apply)
Easy- AGravitational potential energy
- BKinetic energy
- CElastic potential energy
- DChemical potential energy
- EThermal energy
6.Arrange the following energy transformations in the correct order for a swinging pendulum (starting from the highest point):
Medium- Kinetic energy increases
- Potential energy decreases
- Kinetic energy decreases
- Potential energy increases
7.Match each energy type with its correct description:
Easy- Kinetic energy
- Gravitational potential energy
- Elastic potential energy
- Energy of motion
- Energy stored due to height
- Energy stored in a stretched spring
8.In a real pendulum, mechanical energy is conserved because friction is negligible.
MediumTrue or false?
更多題目
9.Which of the following is a non-conservative force?
Easy- AGravitational force
- BElastic spring force
- CFrictional force
- DElectrostatic force
10.Which of the following statements about mechanical energy are true? (Select all that apply)
Medium- AMechanical energy is the sum of kinetic and potential energy.
- BIn an isolated system with only conservative forces, mechanical energy is conserved.
- CFrictional forces always increase mechanical energy.
- DIn an inelastic collision, some mechanical energy is converted to thermal energy.
11.Kinetic energy of an object depends on the square of its speed.
EasyTrue or false?
12.Arrange the following events for a pendulum swinging from its highest point on the left to its highest point on the right, in the order they occur:
Medium- Maximum kinetic energy at the bottom
- Maximum potential energy at the left extreme
- Maximum potential energy at the right extreme
- Potential energy decreasing, kinetic energy increasing
13.A roller coaster car is at the top of a hill. Which energy conversion occurs as it rolls down?
Easy- AKinetic to potential
- BPotential to kinetic
- CChemical to kinetic
- DThermal to potential
14.An electric motor converts mechanical energy into electrical energy.
EasyTrue or false?
15.A 0.2 kg ball is dropped from a height of 5 m. Ignoring air resistance, what is its kinetic energy just before it hits the ground? (Use g = 10 m/s²)
Medium- A10 J
- B1 J
- C0 J
- D5 J
16.A roller coaster car of mass 1000 kg is at the top of a 20 m high hill moving at 2 m/s. It then descends to a point 5 m above the ground. Ignoring friction, what is its speed at that point? (Use g = 10 m/s²)
Hard- A20 m/s
- B10 m/s
- C17.3 m/s
- D18.7 m/s
17.Which of the following are examples of energy transformations where mechanical energy is converted to another form? (Select all that apply)
Medium- AA generator producing electricity from falling water
- BA light bulb producing light from electricity
- CA car's brakes converting kinetic energy to heat
- DA battery powering a flashlight
18.In an elastic collision, kinetic energy is conserved.
EasyTrue or false?
19.Match each scenario to the correct energy transformation.
Medium- A ball thrown upward
- A car coming to a stop
- A roller coaster going down a hill
- Kinetic to potential
- Kinetic to thermal
- Potential to kinetic
20.Arrange the following events for a roller coaster starting from rest at the top of the first hill, going down, then up the next hill, in the order they occur.
Medium- Potential energy decreases, kinetic energy increases
- Kinetic energy decreases, potential energy increases
- Kinetic energy is maximum, potential energy is minimum
- Potential energy is maximum, kinetic energy is zero
21.A 2 kg object is dropped from rest. What is its kinetic energy after falling 3 m? (Use g = 10 m/s²)
Medium- A60 J
- B30 J
- C20 J
- D40 J
22.Which of the following devices converts mechanical energy into electrical energy?
Easy- AElectric motor
- BElectric generator
- CBattery
- DLight bulb
23.In an experiment to investigate the conservation of mechanical energy, a student releases a ball from rest at the top of a ramp and measures its speed at the bottom. Which of the following is the most important reason to use a ramp with a smooth surface?
Medium- ATo reduce the effect of friction so that mechanical energy is approximately conserved
- BTo increase the gravitational potential energy of the ball
- CTo make the ball roll faster
- DTo ensure the ball does not slide
24.A student sets up a pendulum and measures the period for small swings. Which of the following changes would increase the mechanical energy of the pendulum? (Select all that apply)
Medium- AIncreasing the mass of the bob
- BIncreasing the amplitude (starting angle) of the swing
- CReleasing the bob from a higher point
- DShortening the string length
- EAdding a small weight to the bob
25.In an experiment to measure the speed of a trolley rolling down a ramp, using a light gate and data logger, the kinetic energy at the bottom can be calculated if the mass of the trolley is known.
EasyTrue or false?
26.Match each experimental setup with the type of energy conversion it demonstrates.
Medium- Pendulum swinging from a height
- Ball rolling down a ramp
- Compressed spring launching a mass
- Gravitational potential to kinetic
- Elastic potential to kinetic
27.Place the following steps in the correct order for an experiment to determine the speed of a pendulum bob at its lowest point using energy conservation.
Medium- Measure the height of the bob above its lowest point when released
- Record the mass of the bob
- Calculate the speed using v = √(2gh)
- Release the bob from rest
28.A student investigates the relationship between the compression of a spring and the maximum height reached by a ball. Which graph would best represent the expected relationship between compression distance (x) and maximum height (h)?
Medium- Ah proportional to x2
- Bh proportional to x
- Ch proportional to 1/x
- Dh proportional to √(x)
29.In a ball-drop experiment, if the ball is dropped from a height of 2.0 m and the measured speed just before hitting the ground is 5.5 m/s, this indicates that mechanical energy was conserved (use g = 9.8 m/s²).
HardTrue or false?
30.A student performs an experiment where a marble rolls down a curved track and then launches horizontally off a table. The horizontal distance travelled is measured for different release heights. Which of the following is the most likely source of systematic error in determining the speed at launch from the horizontal distance?
Medium- AAir resistance on the marble after launch
- BFriction between the marble and the track
- CInaccuracy in measuring the mass of the marble
- DParallax error when reading the release height
31.Which of the following is the correct formula for kinetic energy?
Easy- AKE = ½ mv²
- BKE = mgh
- CKE = mv
- DKE = ½ m²v
32.Gravitational potential energy depends on which of the following?
Easy- AMass and height
- BMass and speed
- CSpeed and height
- DWeight and speed
33.Energy is a scalar quantity.
EasyTrue or false?
34.In an experiment to verify conservation of mechanical energy for a pendulum, which measurement is most critical?
Medium- AMass of the bob
- BLength of the string
- CSpeed at the lowest point
- DTemperature of the air
35.Which of the following are examples of conservative forces? (Select all that apply)
Medium- AGravity
- BFriction
- CSpring force
- DAir resistance
36.In an inelastic collision, mechanical energy is conserved.
EasyTrue or false?
37.Match each energy form with its correct description.
Easy- Kinetic energy
- Gravitational potential energy
- Elastic potential energy
- Energy stored in a compressed spring
- Energy of motion
- Energy due to height above ground
38.Place the following events for a pendulum swinging from its highest point on the left to its highest point on the right, in the order they occur.
Medium- Maximum kinetic energy at lowest point
- Maximum potential energy at right extreme
- Maximum potential energy at left extreme
39.A student drops a 0.2 kg ball from a height of 2.0 m. She measures its speed just before it hits the ground as 5.5 m/s. What is the best conclusion from this experiment? (Use g = 9.8 m/s²)
Hard- AMechanical energy is conserved because the calculated speed from conservation is about 6.3 m/s, so some energy was lost.
- BMechanical energy is conserved because the measured speed is less than the theoretical speed, indicating gain of energy.
- CMechanical energy is not conserved because the measured speed is greater than the theoretical speed.
- DMechanical energy is conserved because the measured speed exactly matches the theoretical speed.
40.Which of the following statements about the conservation of mechanical energy are true? (Select all that apply)
Medium- AMechanical energy is conserved in a system where only conservative forces do work.
- BIn a real swinging pendulum, mechanical energy is conserved exactly.
- CIn an inelastic collision, mechanical energy is not conserved because some is converted to thermal energy.
- DThe principle of conservation of mechanical energy is an exact law that holds in all situations.
- EWhen a ball is thrown upward and air resistance is negligible, mechanical energy is conserved.
41.Complete the sentence:
EasyThe energy stored in an object due to its position above the ground is called ____ energy.
42.Calculate the kinetic energy of a 2 kg object moving at 3 m/s.
Easy43.What is the principle of conservation of mechanical energy?
Medium44.A 0.5 kg ball is dropped from a height of 10 m. What is its gravitational potential energy relative to the ground? (Use g = 9.8 m/s²)
Easy45.What is the formula for kinetic energy?
Easy46.A 500 g object is moving at 4 m/s. Calculate its kinetic energy in joules.
Easy47.Complete the sentence using the correct word.
MediumWhen a pendulum swings, at the lowest point its kinetic energy is ____ and its potential energy is ____.
48.Define gravitational potential energy.
Easy49.A 2 kg object is moving at 5 m/s. Calculate its kinetic energy.
Easy50.Complete the sentence about energy conservation.
MediumThe principle of conservation of mechanical energy states that the total mechanical energy of an isolated system remains ____ if only ____ forces act.
51.What is the difference between a conservative force and a non-conservative force?
Medium52.A 0.5 kg pendulum bob is released from a height of 0.2 m above its lowest point. Ignoring friction, what is its speed at the lowest point? Use g = 9.8 m/s².
Medium53.Explain why a ball thrown upward has maximum potential energy at the top of its flight.
Easy54.Explain why a real pendulum eventually stops swinging, even though its mechanical energy is conserved in theory.
Medium55.Explain why a real pendulum eventually stops swinging, even though mechanical energy is conserved in theory.
Medium56.Explain the energy transformations that occur when a ball is thrown upward and then falls back down, ignoring air resistance.
Medium57.Describe how you would use a light gate and a data logger to measure the speed of a trolley at the bottom of a ramp, and explain how you would use this to verify conservation of mechanical energy.
Hard58.Calculate the kinetic energy of a 2 kg object moving at 3 m/s.
Easy- A9 J
- B8 J
- C10 J
- D11 J
59.A 0.5 kg ball is dropped from a height of 10 m. What is its gravitational potential energy relative to the ground? (Use g = 9.8 m/s²)
Easy- A49 J
- B59 J
- C54 J
- D44 J
60.A 500 g object is moving at 4 m/s. Calculate its kinetic energy in joules.
Easy- A6 J
- B5 J
- C4 J
- D3 J
61.A 2 kg object is moving at 5 m/s. Calculate its kinetic energy.
Easy- A25 J
- B22 J
- C28 J
- D31 J
62.A 0.5 kg pendulum bob is released from a height of 0.2 m above its lowest point. Ignoring friction, what is its speed at the lowest point? Use g = 9.8 m/s².
Medium- A2.98 m/s
- B0.98 m/s
- C3.98 m/s
- D1.98 m/s
字卡
What are the two main types of mechanical energy?
Kinetic energy (energy of motion) and potential energy (stored energy due to position or configuration).
Define kinetic energy and give its formula.
Kinetic energy is the energy a moving object has due to its motion. Formula: K = ½ mv², where m is mass and v is speed.
Define gravitational potential energy and give its formula.
Gravitational potential energy is energy stored due to an object's height above a reference point. Formula: U = mgh (or U = Wh, where W is weight).
What is the principle of conservation of mechanical energy?
In an isolated system with only conservative forces, the total mechanical energy (U + K) remains constant.
What is a conservative force?
A force where the work done moving an object between two points is independent of the path taken, e.g., gravity.
What is a non-conservative force? Give an example.
A force where the work done depends on the path, e.g., friction. It can convert mechanical energy into thermal energy.
How does energy change in a swinging pendulum (ignoring friction)?
Energy continuously transforms between kinetic and potential. At the bottom, kinetic is maximum and potential minimum; at the extremes, kinetic is zero and potential maximum.
What happens to mechanical energy in a real pendulum with friction?
Mechanical energy is gradually lost (converted to thermal energy) due to air drag and pivot friction, causing the pendulum to slow down.
What is an elastic collision?
A collision in which kinetic energy is conserved (along with momentum). No mechanical energy is converted to other forms.
What is an inelastic collision?
A collision in which some kinetic energy is converted to other forms, such as thermal energy or sound.
Who discovered the equivalence between lost mechanical energy and temperature increase?
James Prescott Joule.
Give an example of a device that converts electrical energy to mechanical energy.
An electric motor.
Give an example of a device that converts mechanical energy to electrical energy.
An electric generator.
What is a heat engine?
A device that converts heat (thermal energy) into mechanical energy.
How does potential energy change when an object is moved opposite to a conservative force?
Potential energy increases because work is done against the force.
What does the kinetic energy of an object depend on?
It depends on the object's mass and the square of its speed.
Is energy a scalar or vector quantity?
Energy is a scalar quantity.
What is the total mechanical energy of a system?
The sum of its potential energy (U) and kinetic energy (K): Emechanical = U + K.
In a closed system with only conservative forces, what remains constant?
The total mechanical energy (U + K) remains constant.
What happens to the speed of an object if its kinetic energy changes?
If kinetic energy increases, speed increases; if kinetic energy decreases, speed decreases (assuming mass constant).
What is the relationship between work and potential energy for a conservative force?
The change in potential energy equals the negative of the work done by the conservative force.
Why can the conservation of mechanical energy be a useful approximation in real systems?
Because non-conservative forces like friction may be negligible, so mechanical energy changes little.