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3 Conservation of energy

A motor transfers 40 J to its own thermal store while lifting a load. It is then switched off and transfers 25 J to the room as it cools.

Considering only these transfers, which statement is correct?

[1]

The motor retains $J15\ \mathrm{J}$ ; the $J25\ \mathrm{J}$ in the room is less useful.

The motor retains $J15\ \mathrm{J}$ ; the $J25\ \mathrm{J}$ in the room is destroyed.

The motor retains $J65\ \mathrm{J}$ ; the $J25\ \mathrm{J}$ in the room is less useful.

The motor retains $J65\ \mathrm{J}$ ; the $J25\ \mathrm{J}$ in the room is destroyed.

3 Conservation of energy Questions

A motor transfers 40 J to its own thermal store while lifting a load. It is then switched off and transfers 25 J to the room as it cools.

Considering only these transfers, which statement is correct?

[1]

The motor retains $J15\ \mathrm{J}$ ; the $J25\ \mathrm{J}$ in the room is less useful.

The motor retains $J15\ \mathrm{J}$ ; the $J25\ \mathrm{J}$ in the room is destroyed.

The motor retains $J65\ \mathrm{J}$ ; the $J25\ \mathrm{J}$ in the room is less useful.

The motor retains $J65\ \mathrm{J}$ ; the $J25\ \mathrm{J}$ in the room is destroyed.