Question

Draw a free-body diagram for each of the following scenarios, labelling each force clearly. Make sure you account for all forces!

a. An elevator that is ascending, hanging from a cable, is coming to a stop.
b. A rocket is being launched straight up, and air resistance is not negligible.
c. You've slammed on the brakes and your car is skidding to a stop while going down a 20-degree hill.
d. A heavy box is in the back of a truck - the truck is accelerating to the left. Draw the box's FBD, and friction is not negligible.

Answer 1

(a) The free body diagram of the elevator that is ascending, hanging from a cable is in the attached image.

(b) The free body diagram of the rocket is in the attached image.

(c) The free body diagram of your car is shown in the image attached.

(d) The free body diagram of the heavy box in the truck is in the attached image.

How to draw the free body diagram of the situations?

(a) The free body diagram of the elevator that is ascending, hanging from a cable consists of;

weight of the elevator acting downwards (W)

tension force of the cable acting upwards (T)

applied force of the elevator (F)

(b) The free body diagram of the rocket consists of;

weight of the rocket acting downwards (W)

air resistance acting downwards (Fs)

applied force of the rocket acting upwards (F)

(c) The free body diagram of your car will consists of;

perpendicular component of the car's weight (mg cosθ)

parallel component of the car's weight (mg sinθ)

the normal force of the car acting upwards

(d) The free body diagram of the heavy box in the truck will consists of;

combined weight of the box and truck acting downwards (W)

the force of friction acting right (Fs)

applied force of the truck acting right (F)

the normal force of the ground acting upwards (N)