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You’re driving at 35 km/h when the road suddenly descends
Chapter 10, Problem 34P(choose chapter or problem)
Problem 34P
You’re driving at 35 km/h when the road suddenly descends 15 m into a valley. You take your foot off the accelerator and coast down the hill. Just as you reach the bottom you see the policeman hiding behind the speed limit sign that reads “70 km/h.” Are you going to get a speeding ticket?
Questions & Answers
QUESTION:
Problem 34P
You’re driving at 35 km/h when the road suddenly descends 15 m into a valley. You take your foot off the accelerator and coast down the hill. Just as you reach the bottom you see the policeman hiding behind the speed limit sign that reads “70 km/h.” Are you going to get a speeding ticket?
ANSWER:
Step 1 of 4
Here we need to calculate the final speed of the car when it reaches the ground near to speed limit sign. The given car is moving initial at \(v_{i}=35 \mathrm{~km} / h\) goes down a valley of height \(h=15 \mathrm{~m}\) and reaches the ground near the speed limit sign
Given data,
Height, \(h=15 \mathrm{~m}\)
Initial velocity, \(v_{i}=35 \mathrm{~km} / \mathrm{h}\)
Using \(1 \mathrm{~km}=10^{3} \mathrm{~m}\) and \(1 \mathrm{hr}=3600 \mathrm{~s}\)
\(v_{i} =35 \frac{\mathrm{km}}{\mathrm{h}}\left|\frac{10^{3} \mathrm{~m}}{1 \mathrm{~km}}\right|\left|\frac{1 \mathrm{fm}}{3600 \mathrm{~s}}\right|\)
\(v_{i} =9.72 \mathrm{~m} / \mathrm{s}\)
The given problem can be pictorially represented as shown below,
