An object falls at terminal velocity in air. What overall conversion of energy is occurring?

A Gravitational potential energy to kinetic energy

B Gravitational potential energy to thermal energy

C Kinetic energy to gravitational potential energy

D Kinetic energy to thermal energy

Describe the energy changes taking place when an apple falling towards the ground.

Describe the energy changes taking place: when a car decelerating when the brakes are applied

Describe the energy changes taking place when a space probe falling towards the surface of a planet.

A $120 \mathrm{kg}$ crate is dragged along the horizontal ground by a $200 \mathrm{N}$ force acting at an angle of $30°$ to the horizontal, as shown.

The crate moves along the surface with a constant velocity of $0.5 \mathrm{m}{\mathrm{s}}^{-1}.$ The $200 \mathrm{N}$ force is applied for a time of $16 \mathrm{s}$.

Calculate the work done on the crate by the $200 \mathrm{N}$ force

A $120 \mathrm{kg}$ crate is dragged along the horizontal ground by a $200 \mathrm{N}$ force acting at an angle of $30°$ to the horizontal, as shown.

The crate moves along the surface with a constant velocity of $0.5 \mathrm{m}{\mathrm{s}}^{-1}.$ The $200 \mathrm{N}$ force is applied for a time of $16 \mathrm{s}$.

Calculate the work done on the crate by the weight of the crate

A $120 \mathrm{kg}$ crate is dragged along the horizontal ground by a $200 \mathrm{N}$ force acting at an angle of $30°$ to the horizontal, as shown.

The crate moves along the surface with a constant velocity of $0.5 \mathrm{m}{\mathrm{s}}^{-1}.$ The $200 \mathrm{N}$ force is applied for a time of $16 \mathrm{s}$.

Calculate the work done on the crate by the normal contact force $\mathrm{N}$.

A $120 \mathrm{kg}$ crate is dragged along the horizontal ground by a $200 \mathrm{N}$ force acting at an angle of $30°$ to the horizontal, as shown.

The crate moves along the surface with a constant velocity of $0.5 \mathrm{m}{\mathrm{s}}^{-1}.$ The $200 \mathrm{N}$ force is applied for a time of $16 \mathrm{s}$.

(b) Calculate the rate of work done against the frictional force $\mathrm{F}$.

Explain which of the following has greater kinetic energy?

• A $20$ -tonne truck travelling at a speed of $30 \mathrm{m}{\mathrm{s}}^{-1}$

• A $1.2$g dust particle travelling at  $150 k\mathrm{m}{\mathrm{s}}^{-1}$ through space