The Physics
Hypertextbook
Opus in profectus

# Forces

## Problems

### practice

1. Draw a free body diagram of…
1. a book lying on a level table.
2. a person floating in still water.
3. a wrecking ball hanging vertically from a cable.
4. a helicopter hovering in place.
2. Draw a free body diagram of a child pushing a wagon on level ground.

### conceptual

1. Draw a free body diagram for each of the following situations…
1. a car that…
1. accelerates forward
2. cruises with a constant velocity
3. brakes to a stop
2. a passenger in an elevator that…
1. ascends from the lobby
2. cruises upwards
3. slows to a stop at the 35th floor
3. a passenger in an elevator that…
1. descends from the 35th floor
2. cruises downwards
3. slows to a stop at the lobby
4. an airplane that does the following (each with a constant velocity)…
1. climbs to cruising altitude
2. cruises horizontally
3. descends to a landing…
2. Draw a free body diagram for each of the following situations…
1. a child pulling a sled by a rope
2. a home owner pushing a lawn mower
3. a wooden crate resting on a wooden ramp with a 37° angle of inclination
4. a child pushing a wagon up a ramp inclined 37° above the horizontal
5. a laboratory pendulum pulled back 37° from vertical by a physics student…
1. immediately before the student released it
2. immediately after the student released it
3. The physicist and author Dr. John Fontanella in the first chapter of his book The Physics of Basketball (paid link) claims to have identified "The Final Four". It's more than just a clever reference for fans of college basketball in the US. Mr. Fontanella has identified the four forces that affect the trajectory of a basketball. Determine these four forces and draw a free body diagram for a basketball after it has left the hands of a player throwing a free throw. Assume a launch at an angle of 51° with backspin — an initial condition that Dr. Fontanella says "results in the softest shot".
4. The Physics Teacher has published several articles containing free body diagram worksheets. They are available free to members of the American Association of Physics Teachers (AAPT). Everyone else has to pay.