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A car is moving with a constant speed of...

A car is moving with a constant speed of `60 km h^-1` on a straight road. Looking at the rear view mirror, the driver finds that the car following him is at a distance of `100 m` and is approaching with a speed of `5 km h^-1`. In order to keep track of the car in the rear, the driver begins to glane alternatively at the rear and side mirror of his car after every `2 s` till the other car overtakes. If the two cars were maintaining their speeds, which of the following statement (s) is/are correct ?

A

The speed of the car in the rear is 65 `kmh^(-1)`

B

In the side mirror, the car in the rear would appear to approach with a speed of 5 `kmh^(-1)` to the driver of the leading car

C

In the rear view mirror, the speed of the approaching car would appear to decrease as the distance between the cars decreases

D

In the side mirror, the speed of the approaching car would appear to increase as the distance between the cars decreases

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The correct Answer is:
To solve the problem, we need to analyze the situation step by step. ### Step 1: Identify the speeds of both cars The speed of the leading car (the car driven by the driver) is given as: - Speed of leading car, \( v_1 = 60 \, \text{km/h} \) The speed of the following car is given as: - Speed of following car, \( v_2 = 5 \, \text{km/h} \) ### Step 2: Convert speeds to the same unit To make calculations easier, we convert the speeds from km/h to m/s: - \( v_1 = 60 \, \text{km/h} = \frac{60 \times 1000}{3600} = 16.67 \, \text{m/s} \) - \( v_2 = 5 \, \text{km/h} = \frac{5 \times 1000}{3600} = 1.39 \, \text{m/s} \) ### Step 3: Calculate the relative speed The relative speed of the following car with respect to the leading car is: - Relative speed, \( v_{rel} = v_1 - v_2 = 16.67 \, \text{m/s} - 1.39 \, \text{m/s} = 15.28 \, \text{m/s} \) ### Step 4: Calculate the time taken to overtake The initial distance between the two cars is \( 100 \, \text{m} \). To find the time taken for the following car to overtake the leading car, we can use the formula: - Time, \( t = \frac{\text{Distance}}{\text{Relative Speed}} = \frac{100 \, \text{m}}{15.28 \, \text{m/s}} \approx 6.54 \, \text{s} \) ### Step 5: Analyze the statements Now we will analyze each statement provided in the question: 1. **Statement A**: The speed of the car in the rear is \( 65 \, \text{km/h} \). - This statement is incorrect because the speed of the following car is \( 5 \, \text{km/h} \). 2. **Statement B**: In the side mirror, the car in the rear would appear to approach with a speed of \( 5 \, \text{km/h} \) to the driver of the leading car. - This statement is incorrect because the speed of the following car relative to the leading car is \( 15.28 \, \text{m/s} \) (or \( 55.28 \, \text{km/h} \)). 3. **Statement C**: In the rear view mirror, the speed of the approaching car would appear to decrease as the distance between the cars decreases. - This statement is correct. As the following car approaches, the image in the rear view mirror appears to move slower due to the relative motion. 4. **Statement D**: In the side mirror, the speed of the approaching car would appear to increase as the distance between the cars decreases. - This statement is incorrect. The speed would not appear to increase; it would appear to decrease as the distance reduces. ### Conclusion The only correct statement is **Statement C**.

To solve the problem, we need to analyze the situation step by step. ### Step 1: Identify the speeds of both cars The speed of the leading car (the car driven by the driver) is given as: - Speed of leading car, \( v_1 = 60 \, \text{km/h} \) The speed of the following car is given as: - Speed of following car, \( v_2 = 5 \, \text{km/h} \) ...
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