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A driver traveling at 22m/s, slows down her 2000kg car to stop for a red light. What work is done by the friction froce against the wheels?

a. -2.2X104 J
b. -4.4X104 J
c. -4.84X105 J
d. -9.68X105 J

User Dobrobobr
by
3.1k points

2 Answers

2 votes

Answer: c. -4.84 × 10^5J

Therefore, the work is done by the friction froce against the wheels is -4.84 × 10^5J

Step-by-step explanation:

Given;

Car velocity v = 22m/s

Mass m = 2000kg

From the law of conservation of energy.

Kinetic energy of the car before stopping K.E= workdone by friction force against the wheels W

W = -K.E .....1

And the kinetic energy of the car can be written as

K.E = 1/2 mv^2 ....2

Substituting m and v into equation 2

K.E = 1/2 × 2000kg × 22^2

K.E = 484,000J

From eqn1

W = -K.E = -484,000J

W = -4.84 × 10^5J

Therefore, the work is done by the friction froce against the wheels is -4.84 × 10^5J

User DanielRead
by
3.5k points
3 votes

Answer:

C -4.84× 10^5J

Step-by-step explanation:

Work done = force × distance

v^2 = u^ +2as

u= 22m/s

a =10m/s^2

When the car stops the final velocity (v) =0

0= 22^2 +2×10×s

s = -484/20

s =-24.2m

Work done = force × distance

Force = mass × acceleration

Work done = 2000×10× -24.2

= -4.84×10^5J

User Petr Matousu
by
3.3k points