Draw a free-body diagram for each of the following objects:
a. a projectile accelerating downward in the presence of air resistance
b. a crate being pushed across a flat surface at a constant speed
a. The free-body diagram for a projectile accelerating downward in the presence of air resistance would have three forces acting on it: gravitational force (mg) pointing downwards, air resistance force (F_air) pointing upwards, and the net force (F_net) pointing downwards.
```
^
F_air|
| |
| |
| |
v F_net
------>
```
b. The free-body diagram for a crate being pushed across a flat surface at a constant speed would have three forces acting on it: gravitational force (mg) pointing downwards, normal force (N) pointing upwards, and the applied force (F_app) pointing to the right.
```
^
F_app |
--------->|
|
|N|
|
|
F_gravity|
v
```