A 90kg student is walking along at a rate of 1.5 m/s. He starts to run and 3 seconds later is moving at a pace of 6m/s. what force have his legs exerted to help him run?

Explain the doppler effect in terms of frequency, wavelength, and speed.

A1,700kg car is being used to give a 1,400kg car a push start by exerting a force of 140n the impulse on the smaller car during the 30.0s of contact is +670kg*m/s. what is the impulse of the smaller car on the larger car? -814 kg*m/s 0kg *m/s -670kg*m/s -550kg*m/s

On a geologic map, if the contacts between sedimentary rock units form a bull’s-eye pattern of concentric circles, with the youngest unit in the center, the underlying structure is a(n)