Click here to go back to KS5 index
science-spark.co.uk

science-spark.co.uk

G481.2 Forces in Action Scheme of Work

G481 Module 2: Forces in action (Lessons 15-25)






Ref: G481.15

Title: F=ma

Group

Date

Period

Room

Objectives – by the end of the session pupils should be able to:
Candidates should be able to:
(a) Solve problems using the relationship: net force = mass × acceleration (F = ma) appreciating that acceleration and the net force are always in the same direction;
(b) define the newton;
(c) apply the equations for constant acceleration and F = ma to analyse the motion of objects;
(d) recall that according to the special theory of relativity, F = ma cannot be used for a particle travelling at very high speeds because its mass increases.

Keywords:
Net (resultant), Force, Newton, acceleration
Einstein, special theory of relativity

Follows from:
Links to:

Starter Activity
What are Newton’s Laws? Newton II – F=ma – we are going to prove it.
Discuss your students’ future results: should find that acceleration is proportional to force, and inversely proportional to mass? Numerically, are their results consistent with the equation F = ma? You may wish to point out that the experiment can only show proportionality. In other words, we can only conclude that: F = kma, where k is a constant. In the SI system of units, we choose k = 1. This defines the Newton: 1 N = 1 kg m s-2.

Development Activity
The affect of mass and force on acceleration

Plenary Activity
Draw graphs

Individuals

Resources:
a trolley, a white plastic track, a pulley, thread, twelve washers (mass 10 g each, or 10 g masses and a folder), metre rule, light gates and timer or stopwatches.

Homework:
Finish graphs and do HW sheets 1, 2 Online

2

Evaluation:


 






Ref: G481.16

Title: F=ma

Group

Date

Period

Room

Objectives – by the end of the session pupils should be able to:
Candidates should be able to:
(a) Solve problems using the relationship: net force = mass × acceleration (F = ma) appreciating that acceleration and the net force are always in the same direction;
(b) define the newton;
(c) apply the equations for constant acceleration and F = ma to analyse the motion of objects;
(d) recall that according to the special theory of relativity, F = ma cannot be used for a particle travelling at very high speeds because its mass increases.

Keywords:
Net (resultant), Force, Newton, acceleration
Einstein, special theory of relativity

Follows from:
Links to:

Starter Activity
Give out graphs that they should get

Development Activity
Questions

Plenary Activity
Go through answers
Hotseat(s)

Individuals

Resources:

Homework:
Find out why F = ma cannot be used for a particle travelling at very high speeds.
Lesson 16 question sheet

3

Evaluation:

 

 






Ref: G481.17

Title: Non-linear motion

Group

Date

Period

Room

Objectives – by the end of the session pupils should be able to:
(a) explain that an object travelling in a fluid experiences a resistive or a frictional force known as drag;
(b) state the factors that affect the magnitude of the drag force;
(c) determine the acceleration of an object in the presence of drag;
(d) state that the weight of an object is the gravitational force acting on the object;
(e) select and use the relationship: weight = mass × acceleration of free fall (W = mg);
(f) describe the motion of bodies falling in a uniform gravitational field with drag;
(g) use and explain the term terminal velocity.

Keywords:

Follows from:
Links to:

Starter Activity
Absorb Physics for A Level to show effect of drag. Multimedia Science.
Demo viscous balls and parachute – terminal velocity. Student prac.

Development Activity
Archery Questions

Ext. More questions.

Plenary Activity
Go through answers.

Individuals

Resources:
ball bearing in oil and magnet for retrieval, stopwatches, metre rules; feathers. Insulating tape. Toy Parachuting soldier

Homework:

4

Evaluation:


 






Ref: G481.18

Title: Equilibrium definitions

Group

Date

Period

Room

Objectives – by the end of the session pupils should be able know:
(a) draw and use a triangle of forces to represent the equilibrium of three forces acting at a point in an object;

Keywords:

Follows from:
Links to:

Starter Activity For the birds – vid http://www.youtube.com/watch?v=ZMmVXOWe5o0
The washing line Take 5 m of good strong string. Ask two pupils to take either end and pull the string taut. Hang a 1kg mass (10 N force) from the middle of the string. The pupils will find it very difficult (impossible, in fact) to keep the string horizontal. Draw a vector triangle of forces. You could finish the discussion with a statement of the principles of equilibrium. For an object to be in equilibrium the forces on it must be balanced; we can check this by resolving in two perpendicular directions. This will give the next activity a sense of a corroborative experiment.

Development Activity
Forces in different directions – ropes, and students pulling.
Forces in equilibrium – masses on pulleys. measuring angles.

 

Plenary Activity
Trolley on a slope

Individuals

Resources:
As sheets: Forces in different directions , Forces in equilibrium
Rope and Kilogram masses

Homework:
Lesson 18 homework

5

Evaluation:

 






Ref: G481.19

Title: moments and couples

Group

Date

Period

Room

Objectives – by the end of the session pupils should be able know:
(b) state that the centre of gravity of an object is a point where the entire weight of an object appears to act;
(c) describe a simple experiment to determine the centre of gravity of an object;
(d) explain that a couple is a pair of forces that tends to produce rotation only;
(e) define and apply the torque of a couple;
(f) define and apply the moment of force;
(g) explain that both the net force and net moment on an extended object in equilibrium is zero;

Keywords:

Follows from:
Links to:

Starter Activity
Define moments and couples. Diagrams of a moment and a coupleand principle of moments: (zero net moment about any point)

Development Activity
Centre of gravity of a student discussion of Conditions for equilibrium Careful questioning will encourage the students to formulate the conditions for equilibrium. They will readily state that the sum of the turning effects must be zero (or words to that effect such as: clockwise moments = anticlockwise moments) but they may need to be reminded that the resultant force must also be zero. 
Weighing a broom
Centre of mass of a non uniform object prac.

Plenary Activity
Worked example

Individuals

Resources:
Retort stand, clamp, String, Slotted masses, metre rules.
2 laboratory stands, 2 newton meters, metre rule, 2 sets of 1 – 10 N weights, string.

Homework:

8

Evaluation:

 






Ref: G481.20

Title: equilibrium examples

Group

Date

Period

Room

Objectives – by the end of the session pupils should be able know:
(h) apply the principle of moments to solve problems, including the human forearm;

Keywords:

Follows from:
Links to:

Starter Activity
Big principle of moments.
Forces on a bridge experiment.

Development Activity
Demo the bookshelf example (extension for mathematically minded)
questions
Questions for forearm too (p39 Heinemann)

Plenary Activity
Answers

Individuals

Resources:
Plank. Book. string, Force meter
2 laboratory stands, 2 Newton meters, metre rule, 2 sets of 1 – 10 N weights, string

Homework:
Lesson 20 HW sheet

9

Evaluation:

 







Ref: G481.21

Title: Density and pressure

Group

Date

Period

Room

Objectives – by the end of the session pupils should be able to:
(i)select and use the equation for density:
      ρ = m / V
(j) select and use the equation for pressure P
             P = F / A
where F is the force normal to the area A.

Keywords:

Follows from:
Links to:

Starter Activity
Use power point to go over use of micrometer and vernier scale.
Measurement activity – using vernier scale and micrometer to measure the length, width and height of different objects. Take the mass of each object.
Watch clip of Holy Grail – witches bit: http://uk.youtube.com/watch?v=zrzMhU_4m-g
 And define density. Define Pressure.

Development Activity
Use measurements to work out the pressure of blocks on the table when placed side by side and stacked on top of each other. And then the density of each.

Pressure and density example questions.

Plenary Activity
Pass the object (to Under Pressure) the student with the object answers question on pressure or density.

Individuals

Resources:
http://www.iom3.org/education/sas.htm (£30 annual membership - speaker will come to school)
Uniform shapes of different materials. Vernier callipers, vernier telescope, micrometer. Electronic balances.

Homework:
Lesson 21 HW sheet.

10

Evaluation:

 






Ref: G481.22

Title: Forces on vehicles

Group

Date

Period

Room

Objectives – by the end of the session pupils should be able to:
(a) define thinking distance, braking distance and stopping distance;
(b) analyse and solve problems using the terms thinking distance, braking distance and stopping distance;
(c) describe the factors that affect thinking distance and braking distance;

Keywords:
Thinking distance
Braking distance
Stopping distance

Follows from:
Links to:

Starter Activity PowerPoint
Show a radio controlled car starting fast on a piece of paper (the paper will be pushed backwards) (whiteboards) Draw a wheel and show the direction of rotation and the push of tyre on the road and the push of road on tyre.
Draw a similar diagram showing a car slowing down. And then one of the torque from the brakes and the engine on the tyre.

Development Activity
Show adverts on stopping distances. Ppt could include brake diagrams. Describe pressure and master and slave cylinders. Make a list and formally define thinking and braking distance. Stopping = thinking + braking.
Friction experiment try with wet and greasy surfaces too.

Plenary Activity
Just a minute. Talk for a minute on motive and braking forces and stopping distances.

Individuals

Resources: Light gate assembly (to measure velocity) plus datalogger/computer, 100g mass, metre rule, suitable surface (e.g. bench top), different surfaces, wet, greasy, etc.

Homework:
Lesson 22 HW sheet

11

Evaluation:

 

 







Ref: G481.23

Title: Car safety

Group

Date

Period

Room

Objectives – by the end of the session pupils should be able to:
(d) describe and explain how air bags, seat belts and crumple zones in cars reduce impact forces in accidents;
(e) describe how air bags work, including the triggering mechanism;
(f) describe how the trilateration technique is used in GPS (global positioning system) for cars.

Keywords:
Air bag
Crumple zone
Seat belt
KE
Force
Work (energy)
Trilateration

Follows from:
Links to:

Starter Activity
Why wear seatbelts? What else do we do to reduce force from impact? How does it work? Think of definition of acceleration. Of time is increased, acceleration is decreased – which is proportional to Force, which is also therefore reduced. Demo egg on a truck, with and without seatbelt. Demo chucking an egg at a wooden board and a sheet. Water balloon demo.

Development Activity
Show ad about speed and cars.
Why speed so important? Surely it’s the mass that does the damage. Think of KE=1/2 m v2 to get them to explain.
Questions

Plenary Activity
Go through answers. Introduce HW. Use this clip to help explain GPS: http://uk.youtube.com/watch?v=3zRlbboMvb0

Individuals

Resources:
Cricket ball. Water balloon. Modified Trolley with seat, ramp, Sellotape, sheet, eggs. Tissue, mop and bucket.

Homework:
Trilateration exercise

12Messy! Check for egg allergies!

Evaluation:

 

 






Ref: G481.24

Title: car safety features

Group

Date

Period

Room

Objectives – by the end of the session pupils should be able to:
Describe the physical principles of seatbelts, air bags and crumple zones.

Keywords:
Air bag
Crumple zone
Seat belt
KE
Force
Work (energy)
Triggering mechanisms

Follows from:
Links to:

Starter Activity
Car crash videos

Development Activity
Student experiment. Making and testing crumple zones. Give 2 sheets of paper each and a specific length of Sellotape.

Plenary Activity
Clean up and prize giving – the golden egg trophy.

Individuals

Resources:
Trolleys, ramp, force meter and data logger, paper, Sellotape.

Homework:
Make a poster on either: seatbelts, crumple zones or airbags and describe how they are activated and work.

13

Evaluation:

 


 






Ref: G481.25

Title: 1.2 Forces in action Test

Group

Date

Period

Room

Objectives – by the end of the session pupils should be able to:
Assess their knowledge and understanding

Keywords:

Follows from:
Links to:

Starter Activity - test

Development Activity

 

 

Plenary Activity
Go through test

Individuals

Resources:
1.2 Forces in action Test

Homework:

14

Evaluation:

 

 

 

2009 science-spark.co.uk