A jet plane lands with a speed of 112 m/s and can accelerate at a maximum rate of −5.40 m/s2 as it comes to rest.
(a) From the instant the plane touches the runway, what is the minimum time needed before it can come to rest?
(b) Can this plane land on a small tropical island airport where the runway is 0.800 km long?

Question

A jet plane lands with a speed of 112 m/s and can accelerate at a maximum rate of −5.40 m/s2 as it comes to rest.
(a) From the instant the plane touches the runway, what is the minimum time needed before it can come to rest?
(b) Can this plane land on a small tropical island airport where the runway is 0.800 km long?

parthkohli · Answer

The three equations of motion with uniform acceleration $a$:$$v_f = v_i + at$$$$d = v_i t + \frac{1}{2}at^2$$$$v_f^2 = v_i^2 + 2ad$$

parthkohli · Answer

For the first question, you need an equation of motion with the following variables:
1. Initial velocity (= 112 m/s)
2. Final velocity (= 0)
3. Acceleration (= -5.4 m/s2)
4. Time (unknown)

Which one would it be? :)

anonymous · Answer

first one....?

parthkohli · Answer

That's correct.

What variables can you use for the second question?

anonymous · Answer

distance

parthkohli · Answer

yes, and what variables do you have known to you?

anonymous · Answer

I got it!!! Thank you! 
20.74 s and No...  Your equations helped a lot :)