Speed and velocity

Yr 9 & Yr 10

1. Distance-time graphs to represent distance travelled against time for uniform motion.

2. Calculating speed from a distance-time graphs.

3. Recall and use the relationship: v = s/t

4. Average speed, v, is total distance covered, s, divided by total time taken to cover distance, t.

5. Units of speed in metres/second (m/s) if distance is measured in metres, time in seconds.

6. Interpretation of distance/time graphs for acceleration

yr 9 Speed.pdf

Acceleration

Yr 10

1. Velocity is the speed of an object in a particular direction at a particular moment

2. Acceleration is the rate of change of velocity.

3. Represent constant velocity and acceleration on distance/time and velocity/time graphs.

4. Recall and use the quantitative relationship: a = (v-u)/t

Calculation of distance travelled, velocity and acceleration from velocity/time graph.

Gravity

Yr 9

1. The difference between mass and weight.

2. Weight of an object is the force of gravity acting on its mass.

3. Mass is measured in kilograms (kg), weight (a force) in newtons (N).

4. Gravity is a force of attraction between objects and depends upon their mass and the distance between them.

5. Acceleration of all freely falling objects in a vacuum near the Earth's surface is the same due to the Earth's gravitational field.

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Force

Yr 10

1. Newton's first law of motion: the velocity of a moving object remains unchanged when acted upon by balanced forces.

2. Newton's second law of motion: the velocity of a moving object is changed (i.e. it accelerates) when acted upon by an unbalanced force.

3. Newton's third law of motion: forces exerted by two interacting bodies on one another other are equal and opposite.

4. The unit of force is the newton. (N)

5. Acceleration depends on the mass of the object and the force applied.

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Friction

Yr 10

Effect of friction on motion, limited to a falling parachute and the friction between a tyre and the road

Terminal velocity as the constant velocity reached by falling objects in air and other fluids.

Factors affecting terminal velocity, limited to

(i) air resistance (drag)

(ii) the shape of an object

Recall and use the quantitative relationship:

where

F = force in Newtons

m = mass in kilograms

a = acceleration in m/s²

Stopping distances

Yr 10

Factors affecting stopping distance of a moving vehicle, limited to

(i) speed of vehicle

(ii) reaction time of driver

(iii) force applied by the braking system

(iv) friction between wheels and surface

(see also kinetic energy)

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