Why is the work output of any real machine less than the work needed to operate it

Classify Cd2 + Mn2 + Kr Zr as Paramagnetic or diamagnetic

Albert Jr. takes his new skateboard out to the top of the loading ramp. The ramp is 30 m long and sloped at an angle of 15 degrees relative to the horizontal. Assuming he starts from rest, and neglecting friction, about how fast is Albert Jr.

What is efficiencywhat is the formula of mechanical advantage and velocity ratio of labour

If body a and b are both within system can forces between them affect the acceleration of the system?

A swing has a period of 10 seconds. What is its frequency?

A swimmer jumps from a waterfall thats is 8.5 m high from the lake below. How fast must he run horizontally to dive 2.5m away from the base of the waterfall?

What happens (as far as energy goes) when a molecule of gas strikes the wall of a container?

The boom of a fire truck raises a fireman (and his equipment - total weight 280 lbf) 60 ft into the air to fight a building fire.

Two masses are separated by 1 m. suppose the masses are moved so they are 2 m apart how will the gravitational force change

Bob rubs a piece of fur on a hand rubber rod, giving the rod a negative charge. what happens?