Question

a bicyclist is traveling at 5 m/s when he begins to brake at 4m/s^2. how fast is he traveling after 5 seconds?

Answer 1

Answer:

He is traveling with 15m/s after 5 seconds.

Explanation:  

Given ,  

Initial velocity$(\mathrm{u})=5 \mathrm{m} / \mathrm{s}$

acceleration $(\mathrm{a})=-4 \mathrm{m} / \mathrm{s}^{2}$

Now, we know that Final Velocity (v) in a uniform acceleration motion  

$\mathrm{v}=\mathrm{u}+\mathrm{at}$

$\mathrm{v}=(5)+(-4)(5) \mathrm{v}=-15 \mathrm{m} / \mathrm{s}$

It means the final direction of the bicyclist at t = 5 secs will be just opposite to its initial direction of motion.  

But speed is asked in this question, so we will take only magnitude not direction. So the speed of bicyclist is 15m/s.