Question

John does 3.2J of work to lower the window shade in her bedroom a distance of 0.8m. How much force must John exert on the window shade?

Answer 1

`\boxed {\boxed {\sf 4 \ Newtons}}}`

Step-by-step explanation:

Work is energy transferred when an object is moved. It is the product of force and distance.

`W= F*d`

John did 3.2 Joules of work or 3.2 Newton meters of work (the units are equivalent). The window shade was lowered a distance of 0.8 meters.

• W=3.2 N*m
• d= 0.8 m

Substitute the values into the formula.

`3.2 \ N *m = F * 0.8 \ m`

We are solving for the force, so we must isolate the variable F. It is being multiplied by 0.8 meters. The inverse operation of multiplication is division, so divide both sides of the equation by 0.8 m.

`\frac {3.2 \ N*m}{0.8 \ m}= ( F* 0.8 \ m)/(0.8 \ m)`

The units of meters cancel.

`\frac {3.2 \ N}{0.8 }=F`

`4 \ N = F`

John must exert 4 Newtons of force.