A rock is dropped from a tower and accelerates at a rate of 9.8 m/s2. It strikes the ground at a speed of 67 m/s. How long did the rock take to reach the ground? (assume no air resistance) Need Soon

Aboy with a mass 25 kg climbs into a small tree. he sits on a branch that is 2.o m above to the ground. what is his gravitational potential energy above the ground?

Which scientist was the first to propose the heliocentric model of the universe? a. aristotle b. isaac newton c. galileo galilei d. nicolaus copernicus

An electromagnetic wave with frequency 65.0 hz travels in aninsulating magnetic material that has dielectric constant 3.64 andrelative permeability 5.18 at this frequency. the electric fieldhas amplitude 7.20 \times 10^{ - 3} {\rm v}/{\rm m}. a. what is the speed of propagation of the wave? b. what is the wavelength of the wave? c. what is the amplitude of the magnetic field? d. what is the intensity of the wave?