A car goes round a bend at a steady 50 km/h; the speedometer needle does not move…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A car goes round a bend at a steady ; the speedometer needle does not move. (a) Is its velocity changing? (b) Is it accelerating? Explain.
Need a reminder? The key ideaShow
Moving round a circle at a steady speed is accelerated motion, because the direction keeps changing. Speed , where is the time for one turn; the frequency is .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Yes. The speed stays , but the direction changes, so the velocity changes.
Step 2. (b) Yes. A changing velocity is an acceleration; it points to the inside of the bend.
Answer: Both yes. The speedometer shows only the speed.
Check. You feel pushed to the outside on a bend: your body tends to go straight on.
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