Question

a projectile can ____. include all that apply.
a. experience a balance of forces
b. be on a surface
c. encounter air resistance
d. have an overall constant speed
e. be moving upwards
f. be moving downwards

Explanation:

• a: A projectile has unbalanced force (gravity, often air resistance), so no force balance.
• b: A projectile is in free fall, not in contact with a surface.
• c: In real-world scenarios, projectiles can encounter air resistance.
• d: Gravity/air resistance change speed, so speed is not constant.
• e: Projectiles (e.g., thrown ball) move upward during flight.
• f: Projectiles (e.g., falling ball) move downward during flight.

Answer:

c. encounter air resistance
e. be moving upwards
f. be moving downwards