Nobject moves with a constant speed of 30 m/s on a circular track of radius 150 m. what is the acceleration of the object

Aproton is projected toward a fixed nucleus of charge +ze with velocity vo. initially the two particles are very far apart. when the proton is a distance r from the nucleus its velocity has decreased to 1/2vo. how far from the nucleus will the proton be when its velocity has dropped to 1/4vo?

Modify the equation fδt=δ (mv) to find the force of friction.

Compare the horizontal displacement of the two balls as they travel to the ground. what do you observe?