Measuring Speed Flashcards

All 6 cards in this deck

What does a light gate connected to a timer actually measure?

The time for which an object (or a card on it) blocks the light beam.

What are the steps to measure the speed of a trolley using a single light gate?

e.g. a card of length 0.05 m blocks the beam for 0.02 s

1. Measure the length of the card on the trolley: 0.05 m
2. Let the card interrupt the beam and record the time: 0.02 s
3. Speed = length ÷ time = $0.05 \div 0.02 = 2.5$ m/s

What is the main advantage of using light gates (or a data logger) instead of a stopwatch to measure speed?

It eliminates human reaction time, so the timing is more accurate.

How can two light gates be used to find the acceleration of a trolley?

Measure the velocity at each gate and the time between them, then use $a = (v-u) \div t$.

What are the steps to measure the average speed of a trolley using a metre rule and a stopwatch?

e.g. a trolley runs along a 2 m bench in 4 s

1. Measure the distance with the metre rule: 2 m
2. Time the whole run with the stopwatch: 4 s
3. Average speed = distance ÷ time = $2 \div 4 = 0.5$ m/s

Apart from using electronic timing, how can the effect of reaction time on a stopwatch measurement be reduced?

Time over a longer distance (longer time), and repeat the measurement to find a mean.