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At what speed does a 1500 kg compact car have the same kinetic energy as a 1.90×10 4kg truck going 24.0 km/hr?

A) 90 km/hr
B) 96 km/hr
C) 105 km/hr
D) 120 km/hr

1 Answer

2 votes

Final answer:

A 1500 kg car must travel at approximately 326.52 km/h to have the same kinetic energy as a 19,000 kg truck going 24.0 km/h, which is not reflected in any of the given options A, B, C, or D.

Step-by-step explanation:

To find the speed at which a 1500 kg compact car must travel to have the same kinetic energy as a 19,000 kg truck going at 24.0 km/h, we use the formula for kinetic energy, KE = ½ mv², where m is the mass and v is the velocity.

First, convert the truck's speed to meters per second by multiplying by 1000/3600. This gives 24 km/h × (1000 m/km) / (3600 s/h) = 6.67 m/s. Then compute the truck's kinetic energy: KE = ½ × 19000 kg × (6.67 m/s)². Now equate this kinetic energy to that of the car and solve for the car's speed: ½ × 1500 kg × v² = ½ × 19000 kg × (6.67 m/s)². Solving for v gives a speed of 90.70 m/s, which is about 326.52 km/h.

But we need to find the answer closest to one of the given options (A, B, C, D), so let's convert 90.70 m/s back into km/h by multiplying by 3600/1000, resulting in the car's speed being approximately 326.52 km/h. However, none of the given options are correct based on the actual calculations.

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