Question

Define positive acceleration. A car starts from rest and attains a
velocity of 72km/h for 10 seconds. Calculate acceleration.

Answer 1

Answer:

Explanation:

1st Part,

Positive acceleration - Increase in velocity with respect to time is known as positive acceleration.

2nd Part,

Given,

Initial velocity, u = 0 m/s (As car starts from rest)

Final velocity, v = 72 km/h = 72 × 5/18 = 20 m/s

Time taken, t = 10 seconds

To Find,

Acceleration, a

Formula to be used,

1st equation of motion, i.e v = u + at

Solution,

Putting all the values, we get

v = u + at

⇒ 20 = 0 + a × 10

⇒ 20 = 10a

⇒ 20/10 = a

⇒ a = 2 m/s².

Hence, the acceleration of the car is 2 m/s².

Answer 2

Given :-

A car starts from rest and attains a

velocity of 72km/h for 10 seconds.

To Find :-

Acceleration

Solution :-

1 km/h = 5/18 m/s

72 × 5/18 = 4 × 5 = 20 m/s

a = v - u/t

a = 20 - 0/10

a = 20/10

a = 2/1

a = 2

Hence

Acceleration is 2 m/s²

Positive Acceleration :- The acceleration in which final velocity is always greater than the initial velocity with respect to the give time

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