Atruck traveling at a constant speed of 40.0 km/h applies its brakes and comes to a complete stop in 5.0 s.
a. convert the truck's constant speed from km/h to m/s.
b. draw a simple v-t graph of the truck stopping. use v = m/s.
c. calculate the average acceleration for the truck. what does this value mean?
d. the truck starts again and accelerates at a constant rate of 0.80 m/s2. beginning at the stopping point of the truck, extend the graph to show 10.0 s of this new constant acceleration.
e. after restarting, how much time does it take for the truck to regain its original speed of 40.0 km/h?
f. after restarting, how far does the truck travel before reaching its original speed of 40.0 km/h?

Part a)

Part c)

This mean the truck is decelerating and its speed is decreasing

Part e)

Part f)

Explanation:

Part a)

Speed of the truck is given as

as we know that

1 km = 1000 m

1 h = 3600 s

so we will have

Part c)

Average acceleration is given as

now we have

Part e)

as we know that it is uniform acceleration

so we can say

Part f)

distance traveled by the truck is given as

a) , b) See attachment below, c) . It means that speed is decreasing at an average rate of 2.222 m/s², d) See attachment below, e) , f) .

Explanation:

a) The constant speed of the truck is:

b) A simple graph is presented as attachment.

c) The average acceleration for the truck is:

It means that speed is decreasing at an average rate of 2.222 m/s².

d) The new graph is present as attachment.

e) The time needed to regain the original speed is:

f) The distance travelled by the truck is:

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.