Chapter 3: Forces
Date:____________
Section 2.2: Projectile Motion and Centripetal Force - Notes
Learning Goals:
 Explain why objects that are thrown will follow a curved path.
 Compare circular motion with motion in a straight line.
Projectile Motion:
 Projectile: anything that is _________________ or _______________
through the air

Thrown objects don’t always travel in ______________________________ – they ________________
______________________________.

This is because the Earth’s ___________________ causes projectiles to follow a
_________________________________.
Horizontal Motion:
 When you throw a ball, the force exerted by your hand ____________ the ball ___________________.

After you let go of the ball, ___________________ is accelerating it forward.
o
The horizontal velocity is ___________________ (ignoring air resistance).
Vertical Motion:

After you let go of the ball, _________________ pulls it ___________________________.

The ball has ____________________ horizontal velocity but _____________________ vertical velocity.
Horizontal and Vertical Motion:

Gravity exerts an ________________________ force on the ball, changing its direction from only
forward to both ___________________________________________________.
o
Results in the ______________________________

Horizontal and vertical motions are _________________________________________
_____________________________

If you throw a ball as hard as you can from shoulder height in a perfectly horizontal direction, would it
take longer to reach the ground than if you dropped a ball from the same height?
o
A thrown ball and dropped ball will hit the ground ___________________________________.
o
Both balls travel the same _______________________ distance in the same
__________________________________________.
o
The thrown ball travels a greater ________________________________ distance.
Centripetal Acceleration:

Centripetal acceleration: acceleration towards the
__________________ of a curved or circular path.
o
In a curve, an object is accelerating because its
_________________________ is constantly changing.

When an object goes around a curve, the direction of the
__________________________ must be towards the
_____________________ of the curved path.
Centripetal Force:

Centripetal force: net force exerted toward the _________________________ of a curved path

When a car rounds a curve, a centripetal force must be acting on the car to keep it moving in a
__________________________________.

In this case, the centripetal force is ________________________
between the tires and the road.

If the road is slippery and the frictional force is small, the centripetal
force may not be _______________________ to keep the car moving
around the curve.
o
The car will slide in a _____________________________.