Using the equation F=m•a What is the mass of a falling rock if it produces a force of 147 N? Hint: This is a free fall problem so a = 9.8m/s/s (acceleration of gravity).

Three point charges, two positive and one negative, each having a magnitude of 20 μc are placed at the vertices of an equilateral triangle (30 cm on a side). what is the magnitude of the electrostatic force on the negative charge

Aparticle initially moving east with a speed of 20.0 m/s, experiences an acceleration of 3.95 m/s, north for a time of 8.00 s. what was the speed of the particle after this acceleration, in units of m/s? give the answer as a positive number.

Use the right-hand rule for magnetic force to determine the charge on the moving particle. this is a charge.