Question

A car of mass 1380 kg, traveling at 31.1 m/s, is brought to rest by the brakes in 48.2 m. Calculate:

(the initial kinetic energy of the car

a) 1.86 x 10^5 J

b) 2.42 x 10^5 J

c) 3.08 x 10^5 J

d) 4.15 x 10^5 J

Answer 1

The initial kinetic energy of a car with a mass of 1380 kg traveling at 31.1 m/s is approximately 668059.9 J or 6.68 x 10^5 J, which doesn't match the provided answer choices, indicating a possible error.

Step-by-step explanation:

The student asked how to calculate the initial kinetic energy of a car with a mass of 1380 kg and a velocity of 31.1 m/s. To find the initial kinetic energy, one can use the formula KE = ½ * m * v2, where KE is kinetic energy, m is mass, and v is velocity.

By plugging in the values provided (m = 1380 kg, v = 31.1 m/s), the calculation is as follows:

KE = ½ * 1380 kg * (31.1 m/s)2 ≈ ½ * 1380 * 967.21 ≈ 668 059.9 J

So the initial kinetic energy of the car is approximately 6.68 x 105 J. However, this does not match any of the answer choices provided, which suggests there may be an error in the question or the provided answer choices. When double checking the calculation and confirming the values and formula are correct, it is important to communicate any discrepancies with the student.