Question

starting from rest, how long does it take moving man to reach a velocity of 5 m/s if his acceleration is 1.75 m/s^2?

Answer 1

Starting from rest, how long does it take moving man to reach a velocity of $5\mathrm{m/s}$ if his acceleration is $1.75\mathrm{m/s}^2$?

Solution:

Let:

$$\begin{array}{l} v = 5 \, \mathrm{m/s} \\ a = 1.75 \, \mathrm{m/s}^2 \\ \end{array}$$ $$\begin{array}{l} S -? \\ S = \frac{1}{2} a t^2 \\ v = a t \Rightarrow t = \frac{v}{a} \\ \Rightarrow \\ S = \frac{v^2}{2a} \\ S = \frac{5^2}{2 \cdot 1.75} = 7.14 \, \mathrm{s} \\ \end{array}$$

Answer: 7.14 s.