## A car starts from rest and accelerates uniformly in a straight line in the positive x direction. After 25 seconds, its speed is 90 km/h.

Question

A car starts from rest and accelerates uniformly in a straight line in the positive x direction. After 25 seconds, its speed is 90 km/h.
a) Determine the acceleration of the object. 
b) How far does the object travel during the first 25 seconds? 
c) What is the average velocity of the object during the first 25 seconds?

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2 months 2021-07-24T20:10:28+00:00 1 Answers 3 views 0

A. 1 m/s²

B. 312.5 m

C. 12.5 m/s

Explanation:

We’ll begin by converting the velocity i.e 90 Km/h to m/s. This can be obtained as follow:

Velocity (Km/h) = 90 Km/h

Velocity (m/s) =?

Velocity (m/s) = Velocity (Km/h) × 1000 / 3600

Velocity (m/s) = 90 × 1000 / 3600

Velocity (m/s) = 90000 / 3600

Velocity (m/s) = 25 m/s

A. Determination of the acceleration.

Initial velocity (u) = 0 m/s

Final velocity (v) = 25 m/s

Time (t) = 25 s

Acceleration (a) =?

v = u + at

25 = 0 + (a × 25)

25 = 0 + 25a

25 = 25a

Divide both side by 25

a = 25/25

a = 1 m/s²

B. Determination of the distance travelled.

Initial velocity (u) = 0 m/s

Final velocity (v) = 25 m/s

Acceleration (a) = 1 m/s²

Distance travelled (s) =?

v² = u² + 2as

25² = 0 + (2 × 1 × s)

625 = 0 + 2s

625 = 2s

Divide both side by 2

s = 625 / 2

s = 312.5 m

C. Determination of the average velocity.

Total distance travelled = 312.5 m

Total time = 25 s

Average velocity =?

Average velocity = Total distance / total time

Average velocity = 312.5 / 25

Average velocity = 12.5 m/s