Which kind of simple machine is NOT part of a bicycle?

What is the equation for calculating a machine's efficiency? I searched all over my textbook and couldn't find it, so I decided to post my question here.

Time management from a stopwatch are not very precise. whynot

A 50 kg box hangs from a rope. what is the tension in the rope if a. the box is at rest? b. the box has vy = 5.0 mis and is speeding up at 5.0 m/s2?

If you are six feet tall how far back from a 3 foot mirror do you have to stand in order to see yourself completely?

A snail crawls 300 cm in 1 hour. Calculate the snail's speed in each of the following units. a. centimeters per hour (cm/h) b. centimeters per minute (cm/min) c. meters per hour (m/h)

Give three examples of situations where you want as little energy as possible to be dissipated.

Which form of cell division creates the sperm and egg, resulting in half of the chromosomes as the other cells?

The effects on marijuana can last up to

A ball is dropped from an initial height and allowed to bounce repeatedly. On the first bounce (one up-and-down motion), the ball reaches a height of 32 inches. On each successive bounce, the ball reaches 75% of its previous height.

An inductor with an inductance of 3.50 H and a resistance of 8.00 Ω is connected to the terminals of a battery with an emf of 4.00 V and negligible internal resistance.