PHYA2 - Speed and Velocity

HideShow resource information
  • Created by: Franklin
  • Created on: 11-05-14 14:53

Speed and velocity

  • Speed: the change in distance per unit time
  • Velocity: the change in displacement per unit time
  • Displacement: distance in a given direction

Motion at constant speed

  • Speed v = s/t
  • circle speed v=2  r/T where T is the time take to move round once
  • Speedgradient of a distance-time graph
  • Velocity = gradient of displacement-time graph
1 of 9

Distance-time graph with variable speed

2 of 9

Displacement-time graph

Gradient of displacement-time graph = velocity, however acceleration is indicated by the curve

3 of 9

Acceleration

Acceleration: the change in velocity per unit time

Acceleration is a vector quantity, deceleration is negative 

4 of 9

SUVAT Equations

5 of 9

Motion Graphs

The case of a ball thrown upwards is used below

  • The ball reaches a maximum height (when velocity is instantaneously zero) then descends
  • Intially the gradient is positive and large because as the ball leaves the hand the velocity is high
  • As the ball rises the velocity decreases because it is acting against gravity
  • As the ball descends the velocity increases due to gravity

Difference between distance-time and displacement time graphs

 Displacement-time graph

6 of 9

Motion Graphs (cont.)

Distance-time graph

7 of 9

Velocity-time and speed-time graphs

The case of a ball thrown upwards is used below

  • The ball reaches a maximum height (when velocity is instantaneously zero) then descends
  • Intially the gradient is positive and large because as the ball leaves the hand the velocity is high
  • As the ball rises the velocity decreases because it is acting against gravity
  • As the ball descends the velocity increases due to gravity

Velocity-time graphs

  • Gradient represents acceleration
  • Area beneath a velocity-time graph is displacement 
  • The positive area represents displacement during ascent since upwards is considered positive
  • The negative area represents displacement during descent since downward is considered negative
8 of 9

Velocity-time graph for ball

 

9 of 9

Comments

No comments have yet been made

Similar Physics resources:

See all Physics resources »See all Motion resources »