(ei) a 150-kg box is pushed horizontally along the floor with a force of 650 n. if the coefficient of friction
between the box and the floor is 0.21, calculate its acceleration.

2.28 m/s²

Explanation:

Draw a free body diagram of the box.  There are four forces on the box:

Weight force mg pulling down.

Normal force Fn pushing up.

Applied force F pushing right.

Friction force Fn μ pushing left.

Sum the forces in the y direction.

∑F = ma

Fn − mg = 0

Fn = mg

Sum the forces in the x direction.

∑F = ma

F − Fn μ = ma

F − mg μ = ma

a = (F − mg μ) / m

a = (650 N − 150 kg × 9.8 m/s² × 0.21) / 150 kg

a = 2.28 m/s²

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

i'm on my way to history not a mistory.