Question

A body starting from rest is moving with uniform acceleration. If it attains a velocity of 72 km/hr in 10 seconds then the acceleration of the body will be ____ m/s2


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Answer 1

Given :

Initial velocity = zero (i.e., rest)

Final velocity = 72 km/hr

Time interval = 10s

To Find :

Acceleration of the body.

Solution :

❒ Acceleration is measured as the rate of change of velocity$.$

• It is a vector quantity having both magnitude as well as direction.
• It can be positive, negative or zero.
• SI unit : m/s²
• CGS unit : cm/s²
• Dimension formula : [L¹T‾²]

First of all we need to convert unit of velocity into metre per second.

We know that, 1 km/hr = 5/18 m/s

∴ 72 km/hr = 72 × 5/18 = 20 m/5

First eq. of kinematics, v = u + at

• v denotes final velocity
• u denotes initial velocity
• a denotes acceleration
• t denotes time

By substituting the given values;

⇒ v = u + at

⇒ 20 = 0 + (a × 10)

⇒ 20 = 10a

⇒ a = 20/10

⇒ a = 2 m/s²