An industrial hydraulic pump consumes a total of 8.40×106 J8.40 \times 10^6\text{ J}8.40×106 J of electrical energy during a lifting cycle. Of this, 6.72×106 J6.72 \times 10^6\text{ J}6.72×106 J is usefully transferred as gravitational potential energy to the load.
Calculate the efficiency of this energy transfer to the load as a proportion.
The power rating of the hydraulic pump is 3.50 kW3.50\text{ kW}3.50 kW. Calculate the time taken for the pump to consume the total 8.40×106 J8.40 \times 10^6\text{ J}8.40×106 J of electrical energy. State the unit.