P1 Force and Motion

P1 Force and Motion

Distance, speed, time

Distance = time * speed

Average speed = total distance / total time

Velocity = speed + direction (vector, whereas speed is scalar)

Acceleration = speed / time

Qualitative understanding: acceleration is the rate of change of velocity per unit of time; the amount of speed changed in a second.

 

Mass and weight

• Mass is the quantity of matter which a body contains, as measured by its acceleration under a given force or by the force exerted on it by a gravitational field – mass resists change in motion.
• Weight = mass * gravity.
• Earth is a source of a gravitational field.

 

Effects of forces

• Force’s unit is newtons (N)
• Forces can change the size (compressions), shape (Stretch) and motion (acceleration) of a body.
• Opposite forces cancel and if they are in equilibrium, the forces are balanced in the system and there is no resultant force.

 

Hooke’s Law

• force = constant × extension (F = kx)
• This direct proportionality will reach a limit whereby the equation no longer applies and the spring reaches maximum extension.

 

P1 Equations

• • Acceleration/Speed with Object: Force = mass * acceleration

 

• Acceleration: speed/time

• Speed: Distance = time * speed

 

• • Pressure: Pressure = force / area (make sure you count how many foots of animal, etc.)
  • Springs: force = constant × extension (F = kx)

 

• Weight: Weight = mass * gravity.