Question

If a body which is initially at rest started moving with an acceleration 2m/s2, then after 3s its velocity is ____.

Answer 1

6 m/s is the required answer.

GIVEN:

• Since the body is initially at rest, its initial velocity, u = 0.
• Acceleration , a = 2 m/s²
• Time , t = 3 s

TO FIND:

Velocity after 3 s, final velocity, v

FORMULA:

• The equations involving u, t, v and a is first equation of motion.

• According to first equation of motion, v = u + at.

SOLUTION:

$v = u + at \\ \\ v = 0 + (2 \times 3) \\ \\ v = 0 + 6 \\ \\ v = 6 \: \frac{m}{s}$

ANSWER:

Velocity after 3 seconds is 6 m/s.

OTHER EQUATIONS OF MOTIONS:

• There are three equations of motion.

• First equation of motion, v = u + at.

• Second equation of motion, s = ut +(at²)/2

• Third equation of motion, v² - u² = 2as

• These three equations of motion can be applied only if acceleration is constant.

• Acceleration should not change with change in time.