Question

A particle is thrown vertically upwards. The correct graph between its speed $\left(v\right)$ and time $\left(t\right)$ is given by (neglecting air resistance).

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

Explanation for Correct Answer,

Option (D):

1. This graph explains that when the particle is moving upward, gravity $\left(g\right)$ acts on it as a decelerator.
2. We know that,$v=u+at$, $v$ is the final velocity, $u$ is the initial velocity.
3. In first half, when particle is thrown upward velocity decreases as the acceleration due to gravity acts downward, $a=-g$
4. $v=u-gt=-gt+u$, $g$ is the gravity, $a$ is the acceleration of the particle
5. This is indicated as a negative slope in the $v-t$ graph.
6. When the body is thrown upwards then it will have some speed which will decrease linearly because acceleration is constant $=-g$.
7. In the second half, when it reaches a maximum height where $v$ becomes zero then again comes back and starts accelerating.
8. This is indicated as a positive slope in the $v-t$ graph.
9. When $v$ becomes zero, speed starts accelerating again as the acceleration due to gravity is acting in the downward direction and the motion of the object is also in the downward direction and the acceleration is constant$=g$.

Hence option D is the correct answer