Kinematics

Question 1

Define Velocity

Answer 1

Velocity= 🔺displacement / time taken

Question 2

Define a scalar quantity

Answer 2

A quantity which has magnitude but no direction.

Question 3

Define a vector quantity

Answer 3

A quantity with both magnitude and direction.

Question 4

Give three examples of a scalar quantity

Answer 4

Distance
Speed
Temperature
Magnitude of acceleration

Question 5

Give three examples of a vector quantity

Answer 5

Displacement
Velocity
Acceleration

Question 6

Define Displacement

Answer 6

The distance travelled in a particular direction. (A vector quantity, it has both magnitude and direction)

Question 7

Define instantaneous speed

Answer 7

The speed of an object at a particular moment

Question 8

Explain an experiment using two light gates to find average speed

Answer 8

-trolley with a card on
-two light gates
-timer
The card breaks the light beam as it passes through the first gate. This starts the timer. The timer stops when the card breaks the second light beam. The speed is calculated from the time interval and the distance between the light gates.

Question 9

Explain an experiment using one light gate to find the average speed

Answer 9

-trolley with card on it
-one light gate
-timer
The timer starts when the leading edge of the card breaks the light beam. It stops when the trailing edge passes through, the light beam is no longer broken. The time shown is the time taken for the trolley to travel a distance equal to the length of the card. The speed is calculated by the distance divided by time.

Question 10

Describe an experiment using a ticker-timer to find average speed

Answer 10

-trolley
-power supply
-ticker-timer
The ticker timer marks dots on the tape at regular intervals (usually 1/50s). The pattern of dots act as a record of the trolley’s movement. Even spacing - constant speed, increasing spacing - increasing speed. Measure the distance of every fifth dot from the start of the tape. This gives the trolley’s distance at intervals of 0.1s. Plot on a table. Draw a distance time graph.

Question 11

Describe an experiment using a motion sensor to find average speed

Answer 11

-motion sensor
-computer
-trolley
The motion sensor transmits regular pulses of ultrasound at the trolley. It detects the reflected waves and determines the time they took for the trip to the trolley and back. The computer can work out the distance from the trolley to sensor. It generates a distance time graph, which can be used to find the speed.

Question 12

Name four experiments to find average speed

Answer 12

• using two light gates
• using one light gate
• using a ticker-timer
• using a motion sensor

Question 13

What do we need to think about when choosing the best experiment to find average speed?

Answer 13

• does the method give an average value of speed or can it be used to give the speed of the trolley at different points along its journey?
• how precisely does the method measure time?
• how simple and convenient is the method to set up?