Physics Forces and Energy Quiz

Lift System

• A lift system uses a cable connected to a counterweight.
• An electric motor powers the lift.
• The counterweight moves down the same distance as the lift moves up.
• The gravitational potential energy of the counterweight decreases as it moves down.

Gravitational Potential Energy Calculation

• Gravitational potential energy (GPE) = mass × gravitational field strength × height
• Use the provided mass and gravitational field strength to calculate any change in gravitational potential energy.

Energy Transformation in a Lift

• Friction between the brakes and the cable causes a decrease in the lift's kinetic energy, leading to an increase in the brakes' internal energy.
• Different factors, such as the distance travelled or the weight of passengers, affect the energy transferred by the motor.

Elastic Potential Energy Calculation

• Elastic potential energy = 0.5 × spring constant × (extension)2
• Use this equation to calculate the elastic potential energy of the cable.
• The mass of the lift and counterweight stretches the cable, acting like a spring.

Lift System Efficiency

• A lift system using a counterweight is more efficient than a lift system that does not use a counterweight.

Trampoline

• A trampoline uses stretched springs to support the sheet of material.
• The child's energy changes from potential to kinetic as the child moves from position A to position B.
• Springs store elastic potential energy, while surroundings store internal energy.
• Calculate the extension of a trampoline spring using its elastic potential energy.

Far-Lepping

• Far-lepping involves an athlete using a long pole to cross a river.
• The athlete's energy changes between kinetic and gravitational potential as they move between positions.
• Calculate the change in gravitational potential energy of the athlete.
• Find the athlete's speed at a particular point given their kinetic energy.

Wood-Fired Hot Tub

• Wood is a renewable biofuel.
• Environmental effects of using wood as energy include deforestation and air pollution.
• Wood, pipe, and water's energy stores change as water heats up.

Eco-House

• Solar panels and wind turbines are renewable energy resources.
• These resources are replenished as they are used and don't produce greenhouse gases.
• Biomass, nuclear, and natural gas are other energy resources.

Bicycle Ride

• The gradient of a distance-time graph is the speed of the bicycle.
• Air resistance and friction are non-contact forces acting on a moving bicycle.
• Calculate the work done using the equation: work done = force × distance.
• As the bicycle moves, work is done against frictional forces, and there's no change in energy in the cyclist's kinetic/gravitational potential energy store.

Gymnast on Parallel Bars

• The upward force acting on a gymnast is the same size as their downward force on the bar.

• Weight is a vector.

• The point from which the weight acts is called the centre of mass/gravity.

• Calculate the weight of the gymnast using the equation weight = mass × gravitational field strength.

• Describe how the gymnast's gravitational potential energy and kinetic energy change as they swing between bars.

Toaster

• The earth wire in a three-core cable is used as a safety measure to prevent the metal case from becoming live in case of a fault.
• Different wires have different colours of insulation, live (brown), neutral (or white), and earth.
• Calculate the energy transferred by the toaster using the equation energy = power × time.
• When bread is in a toaster, a spring inside stores elastic potential energy; the toast moves upwards, generating kinetic energy as its speed increases.

Other Topics

• Calculate the elastic potential energy using the equation: elastic potential energy = 0.5 × spring constant × (extension)2.
• The total energy transferred by the child is a quantity of an equals to the work done by the child.
• Explain why a kangaroo can jump higher as its speed increases.
• Some chip pieces in a deep fryer undergo a physical change and become steam due to heat. No chemicals are involved in this physical change; and it can be reversed when chilled.
• Describe how particles in ice cream vibrate about fixed positions.
• Explain why a can-chiller cools drinks using conduction to transfer energy to the surroundings, and the cooling fins are dark/black, which helps them radiate quicker.
• Describe different processes of energy transfer from hot water in a cup to the surroundings.
• Explain why the temperature of the water doesn't fall below room temperature as the can chiller transfers heat into its surroundings