Question

1.                      An airplane lands with an initial velocity of 70.0 m/s and then decelerates at 1.2 ms-2 for 40.0s. What is its final velocity?​

Answer 1

Provided that:

• Initial velocity = 70 m/s
• Acceleration = -1.2 m/s²
• Time taken = 40 seconds

Don't be confused! Acceleration cames as negative because the airplane decelerates or retards.

To calculate:

• Final velocity

Solution:

• Final velocity = 22 m/s

Using concept:

• First equation of motion

Using formula:

• v = u + at

Where, v denotes final velocity, u denotes initial velocity, a denotes acceleration and t denotes time taken

Required solution:

⇒ v = u + at

⇒ v = 70 + (-1.2)(40)

⇒ v = 70 + (-48)

⇒ v = 70 - 48

⇒ v = 22 m/s

⇒ Final velocity = 22 m/s

Answer 2

Answer:-

• Initial velocity=u=70m/s
• time=t=40s.
• Acceleration=a=-1.2m/s^2
• Final velocity=v=?

Using first equation of motion

$\boxed{\sf v=u+at}$

$\\ \rm\longmapsto v=70+(-1.2(40)$

$\\ \rm\longmapsto v=70+(-48)$

$\\ \rm\longmapsto v=70-48$

$\\ \rm\longmapsto v=22m/s$