Motion in a Straight Line 

Answers

1. Average Speed:

   $$\text{Average speed} = \frac{\text{Total distance}}{\text{Total time}} = \frac{150 \text{ km}}{3 \text{ h}} = 50 \text{ km/h}$$Average speed=Total timeTotal distance​=3 h150 km​=50 km/h

2. Velocity after 5 seconds:

   $$v = u + at = 0 + (2 \text{ m/s}^2)(5 \text{ s}) = 10 \text{ m/s}$$v=u+at=0+(2 m/s2)(5 s)=10 m/s
3. Distance Traveled in 10 seconds:
4. $$s=ut+\frac{1}{2}a{t}^2=0+\frac{1}{2}(1{\text{m/s}}^2)(10\text{s}{)}^2=50\text{m}$$

5. Velocity after 4 seconds:

   $$v=u+at=10\text{m/s}+(3{\text{m/s}}^2)(4\text{s})=22\text{m/s}$$

6. Relative Velocity:

   $$v_{\text{relative}}=80\text{km/h}-60\text{km/h}=20\text{km/h}$$

7. Time to Hit the Ground:

   $$h = \frac{1}{2}gt^2 \implies 45 = \frac{1}{2}(9.8)t^2 \implies t^2 = \frac{90}{9.8} \implies t \approx 3.03 \text{ s}$$
   

8. Deceleration and Distance Covered:

   $$\text{Deceleration}=\frac{\mathrm{\Delta }v}{t}=\frac{20\text{m/s}}{10\text{s}}=2{\text{m/s}}^2$$

Sonika Agarwal