Which of the following has the most momentum? proton (m=1.67 x 10-27 kg) moving at 2.0 x 104 m/s,an electron (m=9.11 x 10-31 kg)
moving at 2.0 x 106 m/s, a common house fly (m=12 mg) moving at 2.0 m/s, North American tectonic plate (m≈5x1022 kg) moving at 3.0x10-10 m/s (about 1cm/yr)
the subatomic particles have very small masses while high speeds, so the product results in values with negative exponents in scientific notation.
Negative exponents also result for the house fly when converting mg into kg (10^-6).
The positive exponents in scientific notation for the momentum come for the gigantic mass of the continental plate which exceeds the negative exponents contributed by the small velocity.
If the object is in equilibrium that means that the sum of the forces on it is zero and the net force is zero. If none of the forces changes then the object continues in constant uniform motion. That means constant speed in a straight line.