Energy Basics
What is energy?
The ability to do work.
What is the formula for kinetic energy?
KE = ½mv²
What type of energy is caused by moving electrons?
Electrical
Calculate KE: 2 kg moving at 3 m/s.
9J
A roller coaster is moving down a hill. What happens to its gravitational potential energy and kinetic energy?
Potential energy decreases while kinetic energy increases.
What unit do we measure energy in?
Joules (J)
What is the formula for potential energy?
PE = mgh
What type of energy comes from the movement of particles?
Thermal
Calculate PE: 5 kg at 2 m.
98J
A ball is dropped from a tall building. At the exact moment it is released, its speed is 0 m/s. Which type of energy is greatest at that moment?
Gravitational potential energy
What is kinetic energy?
The form of energy an object possesses due to its motion.
What does m represent?
Mass
What type of energy is stored in food and batteries?
Chemical
Calculate KE: 5 kg moving at 6 m/s.
90J
A 2 kg ball is falling toward the ground. Explain why its kinetic energy increases as its potential energy decreases.
As the ball loses height, its gravitational potential energy decreases. At the same time, its motion increases, so its kinetic energy increases.
What is potential energy?
Energy stored in an object because of its position, state, or condition.
What does v represent?
Velocity
What type of energy consists of photons?
Light
Calculate PE: 4 kg at 8 m.
313.6 J
Two identical balls are dropped from different heights. Ball A starts at 2 m and Ball B starts at 8 m. Which ball will have more potential energy at the beginning, and why?
Ball B, because it starts at a greater height. The study guide's calculation shows Ball B has 4 times the potential energy of Ball A
Can an object have both kinetic and potential energy?(give an example)
Yes, ex. rollercoaster
What do m, g, and h represent in PE = mgh?
A student eats breakfast before running a race. The food provides stored energy, which is then used by the student's body to move their muscles. As the student runs, their body also produces heat.
A 10 kg object is 5 m high and moving at 10 m/s. Calculate both PE and KE.
PE = mgh
PE = (10)(9.8)(5)
PE = 490 J
KE = ½mv²
KE = ½(10)(10²)
KE = 500 J
A roller coaster is high above the ground and moving quickly. A student says, “The roller coaster can only have potential energy because it is high up.” Is the student correct? Explain.
No. The roller coaster can have both gravitational potential energy and kinetic energy. Its height gives it potential energy, while its motion gives it kinetic energy.