Why is the efficiency of a machine never 100%

Decribe what makes a diamand a mineral

A 45 v battery is connected to a 10.0 ohm resistor in series. What will be the total current in the circuit?

A uniform ladder of mass and length leans at an angle against a frictionless wall. If the coefficient of static friction between the ladder and the ground is, determine a formula for the minimum angle at which the ladder will not slip.

The skydiver has a forward velocity of 40 m/s, After two second, what is the skydivers forward and downward velocity?

a 3.46 kg box is sitting at rest on a flat floor. a.) what is the weight of the box. b.) what is the normal force on the box

A team of dogs is pulling a sled with a net force of 2000 N. The sled is accelerating a 2.2 m/s^2. What is the mass of the sled?

Is the reduction of copper from copper (ii) oxide by carbon exothermic or endothermic? what is the sign of the energy change?

True or false we have mucus that covers are stomach which prevents or stomach acid from digesting or stomach

a man applies a force of 100n to a rock for 60 seconds but the rock does not move what is the amount of work done by the man on the rock

The driver of a car traveling at 32 m/s applies the brakes and undergoes a constant deceleration of 2.25 m/s^2.