Question
Asked Jun 15, 2019
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A car accelerates uniformly from rest to 24.2 m/s in 8.46 s along a level stretch of road. Ignoring friction, determine the average power required to accelerate the car if (a) the weight of the car is 7.73 x 103 N, and (b) the weight of the car is 1.90 x 104 N.

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Expert Answer

Step 1

The initial velocity of car = 0 m/s.

The final velocity = 24.2 m/s.

The time taken  by the car to accelerate =8.46 s.

(a)The power is defined as the change in energy per unit time.

According to work energy theorem, the work done is equal to the change in kinetic energy.

Let mg be the weight of the car,

here, m is the mass
(I)
W =mg
-
Lg is the acceleration due to gravity
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here, m is the mass (I) W =mg - Lg is the acceleration due to gravity

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Step 2

Rearrange equation (I) to obtain an expression for mass, and substitute the corresponding values.

sub stitute, 9.80m/s for g
7.73x 10 N for W
W
m
7.73x10 N
9.80 m/s
800 kg
bo
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sub stitute, 9.80m/s for g 7.73x 10 N for W W m 7.73x10 N 9.80 m/s 800 kg bo

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Step 3

Write the expressio...

change in kinetic energy
P =
time
here, v, is the finalvelocity]
1
v is the initial velocity
t is the time
(II)
t
A.
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change in kinetic energy P = time here, v, is the finalvelocity] 1 v is the initial velocity t is the time (II) t A.

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