energy Flashcards
What are the different ways energy can be stored?
Energy can be stored as kinetic gravitational potential
Describe how energy is transferred between stores during events and processes.
Energy can be transferred by forces (mechanical work done) electrical currents (electrical work done)
State the principle of the conservation of energy.
Energy cannot be created or destroyed; it can only be transferred or transformed from one form to another.
Apply the principle of conservation of energy to a swinging pendulum.
As the pendulum swings gravitational potential energy is converted to kinetic energy at the lowest point and back to gravitational potential energy at the highest point.
What is the formula for kinetic energy?
( E_k = \frac{1}{2}mv^2 ) where ( m ) is mass and ( v ) is velocity.
What is the formula for the change in gravitational potential energy?
( \Delta E_p = mg\Delta h ) where ( m ) is mass
[Alternate-to-Practical] A student drops a ball from a height. Describe the energy changes during the fall.
Gravitational potential energy decreases as it converts to kinetic energy. Air resistance causes some energy to transfer as heat and sound.
[Alternate-to-Practical] Why does a roller coaster have less energy at the end of the ride than at the start?
Some energy is lost to the surroundings as heat and sound due to friction and air resistance.
[Alternate-to-Practical] Describe an experiment to measure the gravitational potential energy of a raised object.
Measure the mass of the object (( m )) using a balance the height (( h )) using a ruler
[Alternate-to-Practical] A 2 kg object moves at 3 m/s. Calculate its kinetic energy.
( E_k = \frac{1}{2}mv^2 = \frac{1}{2} \times 2 \times 3^2 = 9 \text{J} ).
[Alternate-to-Practical] A block of mass 5 kg is lifted 2 m vertically. Calculate the change in gravitational potential energy.
Take ( g = 10 \text{m/s}^2 ). | ( \Delta E_p = mg\Delta h = 5 \times 10 \times 2 = 100 \
[Alternate-to-Practical] What is the energy transformation in an electric motor lifting a weight?
Electrical energy is converted into kinetic energy and gravitational potential energy with some loss as heat and sound.
Explain why a stretched rubber band has potential energy.
The rubber band stores energy as elastic potential energy due to its deformation.
the formula for the work done
work done = force × distance moved in the direction of the force
