Question

Word ProNems:
1. A car goes from 4.47 m/s to 17.9 m/s in 3 seconds.
a. Did this car speed up or slow down?
b. Should your answer be positive or negative? Explain your reasoning.
c. Calculate the acceleration of the car.
​

Answer 1

Answer:

a:it speed up

b:it should be positive since final

velocity is larger than initial velocity

c:acceleration is approximately 4.5

m/s^2

Explanation:

initial velocity=u=4.47m/s

Final velocity=v=17.9m/s

Time=t=3 seconds

a:the car speed up since the velocity

increased

b:change in velocity is positive

because final velocity is larger than

initial velocity

17.9-4.47=13.43 m/s

c: acceleration=(v-u)/t

acceleration=(17.9-4.47)/3

acceleration=13.43/3

acceleration=4.5 m/s^2

Answer 2

• The change in velocity is a positive value, this shows that the car speeds up.

• The answer should be positive since the final velocity is greater than the initial velocity.

• The acceleration of the car is 4.48m/s²

If a car goes from a velocity u to a velocity v, the change in velocity is expressed as;

$\triangle v =v-u$

Given

final velocity v = 17.9m/s

initial velocity u = 4.47m/s

$\triangle v = 17.9-4.47\\\triangle v =13.43m/s$

a) Since the change in velocity is a positive value, this shows that the car speeds up.

b) The answer should be positive since the final velocity is greater than the initial velocity.

c) Acceleration is the change in velocity with respect to time

$a=\frac{v-u}{t}\\a=\frac{17.9-4.47}{3} \\a=\frac{13.43}{3}\\a= 4.48m/s^2$

Hence the acceleration of the car is 4.48m/s²

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