If a 1300-kg car can accelerate from 35 km????h to 65 km????h in 3.8 s, how long will it take to accelerate from 55 km????h to 95 km????h? A

Question

If a 1300-kg car can accelerate from 35 km????h to 65 km????h in 3.8 s, how long will it take to accelerate from 55 km????h to 95 km????h? Assume the power stays the same, and neglect frictional losses.

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Mộc Miên 4 years 2021-08-31T08:29:19+00:00 1 Answers 73 views 0

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  1. thuhuong
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    2021-08-31T08:31:00+00:00
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    Answer:

    6.76 s

    Explanation:

    Power = Energy/time

    P = E/t ………………….. Equation 1

    Where P = Power, E = kinetic energy, t = time.

    But,

    E = 1/2m(Δv)²………………. Equation 2

    Where m = mass of the car, Δv = change in velocity.

    Substitute equation 2 into equation 1

    P = 1/2m(Δv)²/t………………. Equation 3

    Given: m = 1300 kg, Δv = 65-35 = 30 km/h = 30(1000/3600) m/s = 8.33 m/s, t = 3.8 s

    Substitute into equation 3

    P = 1/2(1300)(8.33²)/3.8

    P = 11869.15 W.

    Assuming the power stays the same,

    making t the subject of formula in equation 3

    t = 1/2m(Δv)²/P……………….. Equation 4

    Given: m = 1300 kg, Δv = 95-55 = 40 km/h = 11.11 m/s, P = 11869.15 W

    Substitute into equation 4

    t = 1/2(1300)(11.11²)/11869.15

    t = 6.76 s

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