What force is necessary to accelerate a 70kg object at a rate of 4.2m/s
squared

Positrons are spontaneously emitted from the nuclei of

A1-lb collar is attached to a spring and slides without friction along a circular rod in a vertical plane. the spring has an undeformed length of 5 in. and a constant k =25 lb/ft. knowing that the collar is released from being held at a determine, the speed of the collar and the normal force between the collar and the rod as the collar passes through b.

Awave has a wavelength of 7 mm and a frequency of 19 hertz. what is its speed?