Question

all three questions ​

Answer 1

Answer:

here is your answer.Please correct me if I'm wrong anywhere..

Answer 2

Use the Equations of Motion!

Explanation:

Answer (i) During Time Intervals (0,3) & (5,7) the Body is moving with variable velocity.

Answer (ii) The Acceleration of the Body during Time Intervals 3 seconds -5 seconds is 7.5 m/s ²

As we know that the Acceleration is the ratio of Velocity per unit time.

Velocity during time interval 3-5 (2 seconds) is 15 m/s

So, Here Acceleration =  15/2 = $7.5 \frac{m}{s^{2}}$

Answer (iii) Now for the Displacement, we need to use the equations of motion.

Initial Velocity, u = 15m/s and Final Velocity, v = 0 (As it stops)

Time (t) = 4 seconds

Using v = u + at

0 = 15 + (-a)(4)

a = - 15 / 14

a = 3.75 $\frac{m}{s^{2}}$

Again Using $s = ut + 1/2 a\times{t^{2}}$

$s = {15}\times{4} + 1/2 \times 3.75\times 4^{2}$

s = 60 + 30  

s = 90 m

So, Displacement is 90 m