# Question on motion in a straight line

## Homework Statement

The velocity of a particle moving in positive x axis is according to the relation v= x^2 , then it's acceleration is
A) 8x^2
B) 8x^3
C) 4x^2
D) 4x^3

## Answers and Replies

What is the relation between velocity and acceleration ?

That's it of the question.
I'm pretty confused... I tried differentiation as well

Hint : a = dv/dt and v = dx/dt .

dv/dx = ?
a in terms of v and x ?

TSny
Homework Helper
Gold Member
Show us your attempt at differentiation.

HallsofIvy
Science Advisor
Homework Helper
First, if you have read the sections you were supposed to have read when you registered, you would know that you must show what you have tried! Second, does it not bother you at all that you are asked a problem about "velocity" and "acceleration" and tell us that you do not know what those words mean! I would expect you, if you are expected to be able to do problems like this, to know that velocity is "the rate of change of position with respect to time"- that is, v= dx/dt. You should also know that acceleration is "the rate of change of velocity with respect to time"- that is a= dv/dt.

That is the physics of the situation. You will also need to know some mathematics: the chain rule- If y is a function of x, y(x), and x is a function of t, x(t), then y is also a function of t and dy/dt= (dy/dx)(dx/dt).

• SammyS