Terminal Velocity

1
Terminal Velocity

• Think before you jump

2

• Disregarding air friction, the net force is the
  weight of the object.

Weight mg
3
Disregarding air friction

• All objects in free fall near the earths surface
  accelerate at a constant rate.

4
Taking air friction into account
Air friction
Weightmg

• Air friction depends on speed, surface area,
  shape of object, viscosity of fluid.

5
At terminal velocity, the net force equals zero.
Friction 730 Newtons
Weight 730 Newtons

• Therefore, the acceleration is zero.

6
Acceleration is the rate at which an object
changes its velocity.
7
Terminal velocity occurs when the friction up
equals the weight down.
friction
a 0 m/s2
weight
v constant

• The acceleration will be zero and the velocity
  will be constant.

8
At what rate is the top sky diver advancing on
the lower diver?
V 200 mi/hr
V 120 mi/hr
9
Direct proportion example

• Acceleration is directly proportional to the net
  force applied to the object.

10
Inverse proportion example

• Acceleration is inversely proportional to the
  objects mass.

11
What will happen to acceleration if the objects
mass is doubled?

• The acceleration will be 1/2 of its original
  value.

12
What is the net force on a 1 N apple when you
hold it at rest in your hand?
1 N
Hand
1 N

• Net force is zero, and therefore the apple does
  not accelerate.

13
What is the net force if you let go of the apple?
1 Newton
14
Can the velocity of an object change while it
maintains a constant acceleration?

• Yes, Yes, a thousand times yes.

15
A dropped book accelerates at a constant rate of
10 m/s2 down if we disregard air friction.
16
Velocity is changing but acceleration is a
constant 10 m/s2 down.
V10 m/s
V10 m/s
V20 m/s
V30 m/s