Chapter 3 Notes Pages 43 - 48

Friction Affects Motion Friction is a force Always acts in the opposite of direction the motion Friction

Air Drag Air Drag – the upward force of friction that occurs when an object falls downward through the air.

Amount of friction depends on kinds of material and how much they are pressed together More Friction Less Friction

Why Objects in Free Fall Have Equal Acceleration

Air Drag depends on SPEED and the SURFACE AREA encountered by the air

Definitions Terminal Speed – when acceleration terminates (ex. When air drag equals weight) Terminal Velocity – same definition, but also refers to direction Net force equals zero

# 1 1 N x 1 lb/4.45 N = 0.22 lb

# 2 1 kg weighs 10 N which is the same as 2.2 lb. Star with your weight in pounds, divide by 2.2 and you have your mass in kg. Then multiply by 10 for your weight in Newtons (Your weight in lb) x (1 kg/2.2 lb) x (10 N/1 kg) = your weight in Newtons

The acceleration of each is the same: # 3 a = F/m = 200 N/40 kg = 5m/s2 # 4 The acceleration of each is the same: a = F/m = 2 N/2 kg = 1 N/1 kg = 1 m/s2

# 5 a = F/m = 4(30,000 N)/30,000 kg = 4 m/s2