Linear Motion in Physical Activity

• When a body moves in a STRAIGHT or CURVED LINE with all its parts moving in the SAME DIRECTION & at the SAME SPEED
• Created when an EXTERNAL FORCE is APPLIED THROUGH the COM = DIRECT force

COM - point at which a body's MASS is BALANCED in all directions

1. Law of INERTIA

A body continues ina state of REST/UNIFORM VELOCITY until acted upon by an EXTERNAL force

Inertia - RESISTANCE of a body to CHANGE its STATE of rest/motion

2. Law of ACCELERATION

A body's rate of CHANGE in MOMENTUM is PROPORTIONAL to the SIZE of the force & acts in the SAME DIRECTION

Acceleration - rate of CHANGE in VELOCITY

F=MA

3. Law of REACTION

For every ACTION force there is an EQUAL and OPPOSITE REACTION force

Linear Motion - body moves in a STRAIGHT or CURVED line & at the SAME SPEED

Force - PUSH or PULL that ALTERS a body's state of MOTION (Newtons)

F=MA

Mass - AMOUNT of MATTER in a body (Kg)

M=F/A

Inertia - RESISTANCE of a body to CHANGE its state of MOTION

Momentum - QUANTITY of MOTION possessed by a moving body (kgms)

Momentum = Mass x Velocity

Distance - how FAR a body TRAVELS from A to B (Meters)

Distance = Speed x Time

Displacement - SHORTEST STRAIGHT line route from A to B (Meters)

Displacement = Velocity x Time

Speed - rate of CHANGE of DISTANCE (ms)

Speed = Distance/Time

Velocity - rate of CHANGE of DISPLACEMENT (ms)

Velocity = Displacement/Time

Acceleration - rate of CHANE of VELOCITY (mss)

Acceleration = Change in Velocity/Time

• Indicates the distance travelled by a body over a certain time
• Gradient indicates wheher a body is stationary, at a constant speed, accelerating or deccelerating

Horizontal line (A-B) = no motion

+ve curve (B-C) = acceleration

Diagonal line (C-D) = constant speed

-ve curve (D-E) = decceleration

• Indicates the velocity of a body over a certain time
• Gradient indicates whether the body is stationary, has a unifrom velocity, accelerating or deccelerating

Positive curve (A-B) = acceleration

Negative curve (B-C) = decceleration

Horizontal line (C-D) = uniform velocity

Curve below x-axis (D-E) = change in direction