Question

1. a fridge with a force of kinetic friction of 180 n has a mass of 250 kg. if you would like to push it with an acceleration of 1.1 m/s².

a) draw a fbd and fss’s for this situation.
b) determine the force you will push with.
c determine the net force.

Explanation:

Step1: Recall Newton's 2nd Law

$F_{net} = ma$
$F_{net} = F_{push} - F_{friction}$

Step2: Calculate net force first

$F_{net} = 250\ \text{kg} \times 1.1\ \text{m/s}^2 = 275\ \text{N}$

Step3: Solve for pushing force

Rearrange $F_{push} = F_{net} + F_{friction}$
$F_{push} = 275\ \text{N} + 180\ \text{N} = 455\ \text{N}$

Answer:

a) The free-body diagram (FBD) has:

• Upward normal force ($F_N$)
• Downward gravitational force ($F_g$)
• Rightward applied pushing force ($F_{push}$)
• Leftward kinetic friction force ($F_f$)

The force system diagram (FSS) shows vertical forces are balanced, horizontal forces are unbalanced (net force right).
b) $455\ \text{N}$
c) $275\ \text{N}$