The image above represents reaction: lift moves up.

To compute for reaction: lift moves up, three essential parameters are needed and these parameters are **mass (m), acceleration (a) **and **acceleration due to gravity (g).**

The formula for calculating reaction: lift moves up:

R = m(a + g)

Where;

R = Reaction

m = Mass

g = acceleration due to gravity

a = Acceleration

Let’s solve an example;

Find the reaction when the mass is 18, acceleration is 21 and acceleration due to gravity is 9.8.

This implies that;

m = Mass = 18

g = acceleration due to gravity = 21

a = Acceleration = 9.8

R = m(a + g)

R = 18(21 + 9.8)

R = 18(30.8)

R = 554.4

Therefore, the **reaction **is **554.4 N.**

**Calculating the Mass when the Reaction, the Acceleration and the Acceleration due to Gravity is Given.**

m = ^{R} / _{a + g}

Where;

m = Mass

R = Reaction

g = acceleration due to gravity

a = Acceleration

Let’s solve an example;

Find the mass when the reaction is 42, the acceleration is 21 and the acceleration due to gravity is 9.8

This implies that;

R = Reaction = 42

g = acceleration due to gravity = 9.8

a = Acceleration = 21

m = ^{R} / _{a + g}

m = ^{42} / _{21 + 9.8}

m = ^{42} / _{30.8}

m = 1.36

Therefore, the **mass **is **1.36.**