A car is on cruise control at v=30m/s. If the wind resistance is equal to. F=0.42v² what energy will the car expend to drive 1km?
A)450J
B)378J
C)12.6J
D)378kJ
A car is on cruise control at v=30m/s. If the wind resistance is equal to. F=0.42v² what energy will the car expend to drive 1km?
A)450J
B)378J
C)12.6J
D)378kJ
Answer:
D)378kJ
Explanation:
Applying,
E = F×d……………. Equation 1
Where E = Energy expanded by the car, F = Wind resistance, d = distance
From the question,
F = 0.42v²………… Equation 2
Susbtitute equation 2 into equation 1
E = 0.42v²d………….. Equation 3
Given: v = 30 m/s, d = 1 km = 1000 m
Substitute these values into equation 3
E = 0.42(30²)(1000)
E = 378000
E = 378 kJ
Hence the right option is D)378kJ