SpeedSpeed

D. Crowley, 2008D. Crowley, 2008

SpeedSpeed

To be able to calculate speedTo be able to calculate speed

Wednesday, April 19, 2023

ForcesForces

How can we represent forces?

What forces help movement?

Which hinder it?

How can we represent forces?

What forces help movement?

Which hinder it?

What are contact and non-contact forces?

What type of forces are there?

What are contact and non-contact forces?

What type of forces are there?

ForcesForcesA force is a push or a pull upon an object

Contact forces - two objects in contact with each other

Non-contact forces - a force that acts over a distance

A force is a push or a pull upon an object

Contact forces - two objects in contact with each other

Non-contact forces - a force that acts over a distance

Gravity - non-contact forceFriction (via brake discs) - contact force

ArrowsArrows Arrows are drawn to represent forces

These arrows always work in pairs - if there is a force one way, there will be an opposite force the other way

The bigger the arrow, the bigger the force

Look at the following, and see if you can decide where the force arrows should be…

Arrows are drawn to represent forces

These arrows always work in pairs - if there is a force one way, there will be an opposite force the other way

The bigger the arrow, the bigger the force

Look at the following, and see if you can decide where the force arrows should be…

Apple, on a desk Stationary car Space shuttle, accelerating upwards

Types Of ForceTypes Of Force

• Gravitational Force - acting straight downwards• Magnetic Force - push / pull exerted by a magnet• Electrical Force - a force between two charged objects• Reaction Force - force from the surface, usually acting straight

upwards• Contact Force (push / pull forces) - force which results in the object

speeding up, for example, due to an engine / rocket• Friction - friction between surfaces slowing an object down. This can

include air resistance - (special type of frictional force) where air in the atmosphere slows down a moving object

• Tension Force - pulling of a rope / cable from opposite ends • Elastic Force - compression / extension of a spring or elastic product

• Gravitational Force - acting straight downwards• Magnetic Force - push / pull exerted by a magnet• Electrical Force - a force between two charged objects• Reaction Force - force from the surface, usually acting straight

upwards• Contact Force (push / pull forces) - force which results in the object

speeding up, for example, due to an engine / rocket• Friction - friction between surfaces slowing an object down. This can

include air resistance - (special type of frictional force) where air in the atmosphere slows down a moving object

• Tension Force - pulling of a rope / cable from opposite ends • Elastic Force - compression / extension of a spring or elastic product

ForcesForces

Look at the diagram of the stationary car, car at steady speed, and accelerating car

How can we draw force arrows to represent this?

Look at the diagram of the stationary car, car at steady speed, and accelerating car

How can we draw force arrows to represent this?

Car moving at a steady speed

(balanced force)

Car stationary (balanced force)

Car accelerating (unbalanced force)

SpeedSpeed

To work out the speed of an object, we need to know two things: The distance it has traveled The time taken to travel that distance

The equation needed is

Speed = Distance

To work out the speed of an object, we need to know two things: The distance it has traveled The time taken to travel that distance

The equation needed is

Speed = Distance

Time Time

Speed FormulaSpeed Formula

Speed(s)

Distance(d)

Time(t)

Speed = Distance Time Time = Distance Speed Distance = Speed x Time

ExamplesExamples

Jack ran 100m in 12 seconds. What speed was he traveling at?

Jack then ran 100m again, but this time it was much more windy, and it took him 15 seconds. What was his new speed, and why was this different?

My car was going at 50mph for 1 hour. How many miles did I travel

My car was going at 50mph, and I traveled 20 miles. How long did this take me?

Jack ran 100m in 12 seconds. What speed was he traveling at?

Jack then ran 100m again, but this time it was much more windy, and it took him 15 seconds. What was his new speed, and why was this different?

My car was going at 50mph for 1 hour. How many miles did I travel

My car was going at 50mph, and I traveled 20 miles. How long did this take me?

Speed

Distance

Time

ExamplesExamples Jack ran 100m in 12 seconds. What speed was he traveling at?

Speed = 100 12 = 8.34m/s

Jack then ran 100m again, but this time it was much more windy, and it took him 15 seconds. What was his new speed, and why was this different?

Speed = 100 15 = 6.67m/s (more air resistance)

My car was going at 50mph for 1 hour. How many miles did I travel

Distance = 50 x 1 = 50 miles

My car was going at 50mph, and I traveled 20 miles. How long did this take me?

Time = 20 50 = 0.4 hours (24 minutes)

Jack ran 100m in 12 seconds. What speed was he traveling at?

Speed = 100 12 = 8.34m/s

Jack then ran 100m again, but this time it was much more windy, and it took him 15 seconds. What was his new speed, and why was this different?

Speed = 100 15 = 6.67m/s (more air resistance)

My car was going at 50mph for 1 hour. How many miles did I travel

Distance = 50 x 1 = 50 miles

My car was going at 50mph, and I traveled 20 miles. How long did this take me?

Time = 20 50 = 0.4 hours (24 minutes)

Speed

Distance

Time

Speed ExperimentSpeed Experiment Your task is to work out how your speed can vary - you

are going to travel a distance of 20m by: - Running Walking Skipping Jumping Backwards

You’ll need to time how long it takes you to cover this distance, so when we return we can work out your speed

Speed = Distance Time

Your task is to work out how your speed can vary - you are going to travel a distance of 20m by: - Running Walking Skipping Jumping Backwards

You’ll need to time how long it takes you to cover this distance, so when we return we can work out your speed

Speed = Distance Time

CalculationsCalculations