Unit 1: Motion

Unit 1: Motion

1. Use and describe the use of a stopwatch to measure the period of oscillation of a pendulum

   • 1. Place a refererence marker directly under the pendulum's rest position and observe the pendulum as it repeatedly moves past the marker.
   • 2. Time how long the pendulum takes to undergo a measured number of at least 10 oscillations of the pendulum from when it passes the marker in a certain direction
   • 3. Calculate the average time for the measured number of oscillations: average time for measured number of oscillations / number of oscillations

2. Use and describe the use of a micrometer to measure short lengths accurately

   • A micrometer is used to measure lengths of up to 30mm wide to within 0.01mm.

3. Interpret a distance-time graph to tell if an object is stationary or moving at constant speed or has an increasing/decreasing speed

   • The slope on a distance-time graph represents speed
   • The steeper a distance-time graph is, the greater the speed it represents

4. Make measurements and calculate the speed of a body

   • speed (m/s) = distance travelled (m) / time take (s)

5. Distinguish between speed and velocity

   • Speed and velocity are the same thing except that velocity is 'speed in a given direction'

6. Interpret speed and time data to tell if an object is accelerating and if its accceleration is constant

   • Any object with an increasing speed is accelerating
   • Any object with a decreasing speed is decelerating

7. Use speed and time data calculate the acceleration of an object undergoing constant acceleration

   • The acceleration of an object is its change of veloctiy per second
   • acceleration (m/s2) = change in velocity / time taken

8. Use a speed-time graph to tell us about acceleration from the slope and distance travelled from the area under the graph

   • The area under a speed-time graph represents distance travelled

9. Recall that objects in free fall accelerate at constant acceleration and that air resistance is negligible

   • The acceleration of a freely falling body near to the Earth's surface is constant
     • Any object released near the Earth's surface falls at a constant acceleration, provided air resistance is insignificant. Such motion is described as free fall
   • Using a camera and a light flashing at a constant rate, the photograph can show the distance between successive images of the object, increases as it falls. This means that the object's speed increases as it falls.
     • If results were put into a speed-time graph, there would be a constant slope. This shows that the speed of the falling weight increased steadily - the object fell at constant acceleration

10. Explain why an object falls at terminal speed if air resistance is not negligible

    • The acceleration of a frelly falling object near the Earth is 10m/s2
    • The air resistance (or drag force) on any falling object increases as it gains speed. If it continues to fall, the increasing air resistance causes it to reach a constant speed, referred to as its terminal speed. At this speed, the air resistance on the object opposes the force of gravity with an equal force.

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