Question

A lorry travels along a rough road at 30km for 30mins. If the lorry joins a tarred road and moves at 550km for 1hour.Calculate the average speed of the lorry in m/s

Answer 1

Answer on Question #48621, Physics, Mechanics - Kinematics - Dynamics

A lorry travels along a rough road at 30km for 30mins. If the lorry joins a tarred road and moves at 550km for 1hour. Calculate the average speed of the lorry in m/s

By the definition, average speed is:

$$v_{av} = \frac{S_{total}}{t_{total}}$$

To find time in hours:

$$t_{h} = \frac{t_{min}}{60}$$

So, average speed is:

$$v_{av} = \frac{S_{1} + S_{2}}{\frac{t_{1}}{60} + t_{2}}$$ $$v_{av} = \frac{30km + 550km}{\frac{30}{60}h + 1h} \approx 387 \frac{km}{h} = \frac{387}{3.6} \frac{m}{s} \approx 107 \frac{m}{s}$$

Answer: Average speed: $v_{av} \approx 107 \frac{m}{s}$

Check the values in the task, because the speed is too high.

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