Question

Multiple choice. Need good explanation. Just started with this topic.1.2

Answer 1

Given:

Car P and Q are travelling toward each other.

The speed of P is,

$v_p=10\text{ m/s}$

Acceleration of car P is,

$a_p=2\text{ m/s}^2$

The speed of Q is,

$v_q=20\text{ m/s}$

The cars meet after 5 s.

Acceleration of car Q is,

$a_q=1\text{ m/s}^2$

To find:

The graph of V-T of the cars

Explanation:

The slope of v-T graph shows the acceleration of the object.

AS the cars both have acceleration, the speed vs time graph will be a straight line with positive slopes.

The speed of P in 5 s is,

$\begin{gathered} v_p=10+2\times5 \\ =20\text{ m/s} \end{gathered}$

The speed of Q after 5 s,

$\begin{gathered} v_q=20+1\times5 \\ =25\text{ m/s} \end{gathered}$

The graphs will not intersect each other after 5 s.

Hence, the third one is the correct graph.