Fig. 1 shows equipment used to time a metal trolley travelling down a ramp. A card fixed to the trolley passes through two light gates. The data logger meas...
Question 1 Report
Fig. 1 shows equipment used to time a metal trolley travelling down a ramp. A card fixed to the trolley passes through two light gates. The data logger measures the time between the gates. The distance between the light gates is 0.80 m. A student adds small masses to the trolley box but keeps the ramp angle unchanged.
(a) State the instrument used by the data logger to measure the time interval. [1]
(b) Describe how the student can calculate the average speed of the trolley between the light gates. [2]
(c) Calculate the average speed when the measured time is 0.40 s. [2]
(d) Explain why adding mass to the trolley does not necessarily make its acceleration down the ramp greater. [3]
Answer Details
(a) The data logger uses light gates to measure the time interval. [1]
(b) Use the known distance between the light gates [1] and divide it by the measured time interval:
\[\text{average speed}=\frac{\text{distance}}{\text{time}}\]
[2]
(c) \[\text{average speed}=\frac{0.80\text{ m}}{0.40\text{ s}}=2.0\text{ m/s}\]
The average speed is 2.0 m/s. [2]
(d) Increasing mass increases the downhill component of the trolley's weight. [1] But it can also increase friction or other resistive forces. [1] As acceleration depends on resultant force divided by mass, \(a=F_{\text{resultant}}/m\), the acceleration may remain the same and need not increase. [1]
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