Use the following data for Questions :
Table 3-1; Table 3-2; q = nCΔT; w = Force*distance; ΔE = q + w
-How many kJ of energy will be converted to heat when a 1.4 x 10³ kg automobile stops from a speed of 67 km/hr?

Question

Quizplus · Accepted Answer

The correct answer is A because the change in energy is equal to the heat transferred to the environment, which is given by q = nCΔT. The heat transferred to the environment is equal to the negative of the work done by the automobile, which is given by w = Force*distance. The force acting on the automobile is equal to the mass of the automobile times the acceleration of the automobile, which is given by F = ma. The acceleration of the automobile is equal to the change in velocity divided by the time it takes to stop, which is given by a = Δv/Δt. The time it takes to stop is equal to the distance traveled divided by the speed of the automobile, which is given by t = d/v. Substituting all of these equations into the equation for the change in energy, we get:ΔE = q + w = -F*d = -ma*d = -m(Δv/Δt)*d = -m(v^2/2d)*d = -mv^2/2Plugging in the values for the mass of the automobile and the speed of the automobile, we get:ΔE = -1.4 x 10^3 kg * (67 km/hr)^2 / 2 = -240 kJTherefore, the correct answer is A.

Use the Following Data for Questions