Answer quickly please! Calculate the efficiency of the following devices:
a A lawnmower which converts 143 J out of every 450 J of electrical input
energy into sound and heat. The rest of the energy is converted to kinetic
energy of the blades attached to the motor.

The sun's gravitational pull is weaker on the planets that are closer to it, i think.

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other

Electricity and discharge