Question

A ball which is thrown vertically upwards at 1.2 ms decelerates uniformly at 10 ms.How long will it take to reach zero velocity?​

Answer 1

Answer:

0.12 s

Explanation:

Use v=u+at,

a=-10, v=0, u=1.2,

t=0.12

Answer 2

Answer:

$\bigstar{\bold{Time\:taken=0.12\:s}}$

Explanation:

$\Large{\underline{\underline{\bf{Given:}}}}$

• Initial velocity (u) = 1.2 m/s
• Deceleration (a) = -10 m/s²

$\Large{\underline{\underline{\bf{To\:Find:}}}}$

• Time taken to reach 0 velocity

$\Large{\underline{\underline{\bf{Solution:}}}}$

→ Here final velocity v = 0

→ By Newton's first equation of motion,

  v = u + at

→ Substituting the given datas we get,

 0 = 1.2 × -10t

-1.2 = -10t

   t = 1.2/10

   t = 0.12 s

$\boxed{\bold{Time\:taken=0.12\:s}}$

$\Large{\underline{\underline{\bf{Notes:}}}}$

→ Acceleration is the rate of change of velocity. It's unit is m/s²

→ Negative acceleration is called deceleration or retardation.

→ Newton's three equations of motion are:

• v = u + at
• s = ut + 1/2 × a × t²
• v² - u² = 2as