It takes a truck 3.56 seconds to slow down from 112 km/h to 87.4 km/h. what is its average acceleration?
1.92 m/s2
−1.92 m/s2
−6.81 m/s2
6.81 m/s2

option B

−1.92 m/s2

Explanation:

Given in the question,

time took by truck to slow down = 3.56 sec

initial speed of truck = 112 km/h

final speed of truck = 87.4 km/h

1 km/h = 0.277778 m/s

112 = 31.1 m/s

87.4 = 24.28 m/s

Formula use to calculate the acceleration

v - u = at

where v is final speed

           u is initial speed

           a is acceleration

           t is time

plug values in the equation

24.28 - 31.1 = a(3.56)

-6.8 = a(3.56)

a = -6.8 / 3.56

a = -1.9 m/s²

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.