Grade 8 Physical Science Quiz: Potential and Kinetic Energy

What is the formula for calculating mechanical energy?

• Mechanical Energy = Force x Distance

• Mechanical Energy = Potential Energy + Kinetic Energy

• Mechanical Energy = Mass x Acceleration

• Mechanical Energy = Work / Time

Explain the concept of mechanical energy with an example.

• A car parked on the side of the road has mechanical energy because it is not moving

• A roller coaster at the top of a hill has potential energy, and as it goes down the hill, the potential energy is converted to kinetic energy.

• A book sitting on a shelf has mechanical energy because it is not doing any work

• A person standing still has mechanical energy because they are not in motion

State the law of conservation of energy.

• Energy cannot be created or destroyed, only transformed from one form to another.

• Energy can only be transformed into matter

• Energy can be transformed into unlimited forms

• Energy can be created and destroyed at will

How is the conservation of energy applied in real-life situations?

• Relying solely on non-renewable energy sources

• Energy-efficient appliances, renewable energy sources, and energy conservation practices

• Wasting energy without any regard for efficiency

• Using energy without any consideration for conservation

Define kinetic energy and provide an example of its calculation.

• Kinetic energy is the energy an object possesses due to its position. It is calculated using the formula: KE = m * g * h, where KE is the kinetic energy, m is the mass of the object, g is the acceleration due to gravity, and h is the height of the object.

• Kinetic energy is the energy an object possesses due to its temperature. It is calculated using the formula: KE = 3/2 * n * R * T, where KE is the kinetic energy, n is the number of moles, R is the gas constant, and T is the temperature.

• Kinetic energy is the energy an object possesses due to its motion. It is calculated using the formula: KE = 0.5 * m * v^2, where KE is the kinetic energy, m is the mass of the object, and v is its velocity.

• Kinetic energy is the energy an object possesses due to its shape. It is calculated using the formula: KE = 0.5 * m * a^2, where KE is the kinetic energy, m is the mass of the object, and a is its acceleration.

What factors affect the kinetic energy of an object?

• Temperature and pressure

• Density and volume

• Mass and velocity

• Color and shape

Explain potential energy and its relationship with an object's position.

• Potential energy is the energy an object has due to its speed and motion.

• Potential energy is the energy an object has due to its position relative to other objects.

• Potential energy is the energy an object has due to its color and appearance.

• Potential energy is the energy an object has due to its temperature and heat content.

Calculate the potential energy of a 5kg object placed 10 meters above the ground.

• 100 J

• 200 J

• 490 J

• 50 J

Write the equation for calculating kinetic energy.

• KE = 0.5 * m * v

• KE = m * v^2

• KE = m + v^2

• KE = 0.5 * m * v^2

Derive the equation for potential energy.

• PE = 1/2mv^2

• PE = Fd

• PE = mgh

• PE = mc^2