Drawing distance, speed, acceleration vrs time graphs

NB: The slope of the ramp must stay constant and should be small

ramp

trolley

maskLG1 LG2

1. Distance verse time

The light gates should be connected to a QED set to gap time. This measures the time between LG1 and LG2.

Find this time at 5 different distances and draw a graph.

timedistance

2. Speed verses time

Use one light gate and set QED to instantaneous speed.

Measure the speed at the same distances down the ramp as before. This will allow you to draw a speed time graph.

3. Acceleration verses time

Use one light gate and the double mask.

Measure the acceleration at the same distances down the ramp as before. This will allow you to draw an acceleration time graph.

time

time

speed

speed

play

Projectiles

The only force which acts on a projectile is the force due to gravity ( weight)

v

v

We need to resolve the velocity into its horizontal and vertical components

t

vH

t

vv

Horizontal velocity Vertical velocity

Down

+ ve

No force in horizontal direction so constant velocity

Weight acts downward so accelerates at 9.8 m/s2

down

ExampleA car travelling with a horizontal speed of 20 m/s goes off the top of a cliff. It lands 30 m from the foot of the cliff (i) How high was the cliff? (ii) What was the car’s velocity just before it hit the ground ?

Tutorial questions page 31/32 Qu 1 to 3

Purple book Ex 1.4

Extra questionsatellite

ExampleA basket ball player throws the ball at 600 to the horizontal with an initial speed of 5 ms-1

(a) Calculate the initial horizontal and vertical components of velocity.

(b) The maximum height of the ball above its initial position.

(c) The horizontal range.

Tutorial page 32 to 35 Qu 4 to 12

Purple book Ex 1.5

Estimate your take off velocity in a standing long jump.

Step 1 Vertical jump Measure maximum vertical displacement, sv

Calculate initial vertical velocity, uv and then the time for jump, t.

Step 2 standing long jumpsh maximum horizontal distanceassume you stay in the air for the same length of

time as your vertical jump ie uv and t will be the same as step 1.Calculate the horizontal velocity, vH

Step 3 calculate take off velocity from uv and uH

Do you think the assumption in step 2 is justified?If not, is the calculated value for horizontal velocity too big or too small?The world record for the standing long jump is 3.71 m