EmSAT EmSAT Physics 2 — Questions and Answers
Question 1: What is the formula for kinetic energy?
- KE = mgh
- KE = ½mv² (Correct answer)
- KE = Fd
- KE = mv
Correct answer: KE = ½mv²
Kinetic energy is KE = ½mv², where m is mass (kg) and v is velocity (m/s). It is the energy an object possesses due to its motion.
Question 2: A 2 kg object is lifted 5 m. What is its gravitational potential energy? (g = 10 m/s²)
- 10 J
- 100 J (Correct answer)
- 50 J
- 20 J
Correct answer: 100 J
PE = mgh = 2 × 10 × 5 = 100 J. Gravitational potential energy depends on mass, gravity, and height.
Question 3: What is the law of conservation of energy?
- Energy can be created from nothing
- Energy is always lost as heat
- Total energy in a closed system remains constant (Correct answer)
- Force equals mass times acceleration
Correct answer: Total energy in a closed system remains constant
The law of conservation of energy states that energy cannot be created or destroyed; it can only be transformed from one form to another. The total energy in a closed system remains constant.
Question 4: What type of energy does a compressed spring possess?
- Kinetic energy
- Thermal energy
- Elastic potential energy (Correct answer)
- Chemical energy
Correct answer: Elastic potential energy
A compressed spring stores elastic potential energy. When released, this energy converts to kinetic energy as the spring returns to its natural shape.
Question 5: What is the unit of energy?
- Newton
- Watt
- Pascal
- Joule (Correct answer)
Correct answer: Joule
The SI unit of energy is the Joule (J), defined as 1 kg·m²/s². The watt (W) is the unit of power (energy per unit time).
Question 6: A machine does 500 J of work in 10 seconds. What is its power?
- 5000 W
- 50 W (Correct answer)
- 500 W
- 5 W
Correct answer: 50 W
Power = Work ÷ Time = 500 J ÷ 10 s = 50 W.
EmSAT EmSAT Physics 2
What is the formula for kinetic energy?