physics energy

How can energy be conserved in daily activities?

• Using stairs instead of elevators

• Driving instead of biking

• Increasing the use of air conditioning

• Leaving electronics on standby mode

Answer explanation

Using stairs instead of elevators helps conserve energy by reducing electricity usage and promoting physical activity.

What information is needed to estimate an elevator's power requirement?

• The rated capacity and transport time between floors

• The number of buttons inside the elevator

• The elevator's maximum speed

• The elevator's color

Answer explanation

To estimate an elevator's power requirement, the rated capacity and transport time between floors are needed as they directly impact the energy consumption.

What happens to a car's initial kinetic energy when it comes to a full stop?

• It disappears

• It converts into potential energy

• It is transferred to the road

• It converts into another form of energy

Answer explanation

When a car comes to a full stop, its initial kinetic energy converts into another form of energy.

What happens to a car's initial kinetic energy when it comes to a full stop?

• It disappears

• It converts into potential energy

• It is transferred to the road

• It converts into another form of energy

Answer explanation

When a car comes to a full stop, its initial kinetic energy converts into another form of energy.

What is the principle behind the conservation of mechanical energy in a pendulum's swing?

• Energy is created at the highest point of the swing

• Energy is destroyed at the lowest point of the swing

• Kinetic and potential energies are interconverted but their sum remains constant

• Energy is transferred to the surrounding air

Answer explanation

The principle behind the conservation of mechanical energy in a pendulum's swing is that kinetic and potential energies are interconverted but their sum remains constant.

What factor most significantly affects the efficiency of a solar panel?

• The color of the solar panel

• The angle of sunlight incidence

• The number of solar panels connected in series

• The brand of the solar panel

Answer explanation

The angle of sunlight incidence is the factor that most significantly affects the efficiency of a solar panel.

How does increasing the surface area of a wing affect an airplane's lift?

• Decreases the lift due to increased weight

• Has no effect on the lift

• Increases the lift by allowing more air to push against the wing

• Increases the lift by reducing air resistance

Answer explanation

Increasing the surface area of a wing allows more air to push against the wing, resulting in increased lift.

A man of mass 50 kg jumps to a height of 1 m. His potential energy at the highest point is(g = 10 m/s²)

• (a) 500 J

• (b) 50 J

• (c) 5 J

• (d) 5000 J

Complete the statement about the principal of Conservation of Energy.

Energy can be changed for one form to another but the total amount of energy

• always increases

• always decreases

• does not change

• varies according to the reaction

(Higher level only)What is the Formula to calculate energy transfer for Kinetic Energy?

• E_k=1/2 mv²

• 1/2mv=k

• Em²⁼1/2^k

• EK² =2mv