Steady Motion

Steady Motion

How do objects move at a steady speed?

Starter:

Describe the forces acting on a car moving at a steady velocity of 60mph, forwards.

Revision card

• Make a revision card for momentum.

6 mark question

• Use the idea of momentum to explain why cars are built with crumple zones.

Marks SPAGWhat a crumple zone is/ where they are on a car.How a crumple zone reduces the force on a person.Use of the correct momentum equation.What happens if no crumple zone.

Learning Outcomes

1) explain that, when an object travels at a steady velocity, there is no change of momentum.

2) explain that no resultant force is required to keep an object moving in a straight line at a steady speed

Speed – Time – graph

For each of the 4 stages, draw a force diagram to show what is happening.

A

BC

D

Time

Speed

Mini Plenary worksheet.

explain that no resultant force is required to keep an object moving in a straight line at a steady speed

What are these strange people trying to do?

• Curling

On the floor

On Ice

On “perfect” ice the kettle never stops, it stays at a steady speed. Why?

Lets investigate -

• Which surface is closest to “perfect ice”?

Surface Force needed to move object (N)

Steady Speed and Momentum

• Look at the equations for momentum and work out why at a steady speed, momentum of an object does not change.

6 mark question

• Use the idea of momentum to explain why cars are built with crumple zones.

Marks SPAGWhat a crumple zone is/ where they are on a car.How a crumple zone reduces the force on a person.Use of the correct momentum equation.What happens if no crumple zone.

Round the Room Questions

Task

• Write 5 momentum questions of your own, and produce a marking scheme.

• Swap with neighbour, complete their questions and WWW/ EBI them.

Look at the objectives – how are we doing?