Which of the following could not be responsible for the acceleration of an object? wind gravity density friction

The correct answer to this question is D) Density

EXPLANATION:

From Newton's second laws of motion, we know that the external force acting on a body is equal to the product of mass with the acceleration of the body.

Mathematically Force F = m × a

Here, m is the  mass of the body.

a is the acceleration of the body.

Hence, it is the force which is responsible for creating acceleration in an object.

In the given question, we have four factors i.e wind, friction, gravity and density.

Out of the four options, wind, friction and gravity can exert force on an object and can create acceleration in it.

The density of a body is defined as the mass of that body per unit volume.

Mathematically it is written as -

Density d = \frac{m}{v} where v is the volume occupied by the body.

Hence, density will not be responsible for the acceleration of the body.

i think its

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask