Muscles in animals are often found in pairs, because

A. muscles can only produce a force as they relax.

B. muscles can only pull.

C. muscles need to be able to both push and pull.

D. muscles can only push.

A 0.15-kg ball is thrown into the air and rises to a height of 20.0 m. How much kinetic energy did the ball initially have?

A substance has a volume of 10.0 cm3 and a mass of 89 grams. What is its density? 0.11 g/cm3 8.9 g/cm3 99 g/cm3 79 g/cm3

Kinematic: An object drop 20m from a cliff. If it started at rest and is going 20m/s just before it hits the ground, what is it's acceleration?

Astronomers think most galaxy interactions took place at redshifts of greater than 1 because

A 500-Ω resistor, an uncharged 1.50-μF capacitor, and a 6.16-V emf are connected in series. (a) What is the initial current? (b) What is the RC time constant? (c) What is the current after one time constant?

How do mountins building and volcanos relate to plate motion at convergent boundaries

A 20kg box is dropped 13m. how much work is done

Suppose a person whose mass is m is being held up against the wall with a constant tangential velocity v greater than the minimum necessary. Find the magnitude of the frictional force between the person and the wall

A ball is being rolled by a normal push of 1000N. it is opposed by friction which has a force of 0.3kN and air resistance which has a force of 23N. Calculate the resultant force.

Consider a Young's two-slit experiment in which the wavelength of light is 37% smaller than the distance between the slits.