A stone is thrown straight up in the air. If g represents the acceleration due to gravity, which one of the following statments about the stone is false?
When the stone reaches the top of its flight, its acceleration is still g.
As the stone rises, its potential energy decreases.
When the stone reaches the top of its flight, its energy is zero.
As the stone rises, it is accelerated downward.
As the stone rises, its kinetic energy decreases.

The correct false statement is;

As the stone rises, its potential energy decreases

Explanation:

When the stone is thrown straight up into the air, the initial velocity, u, progressively decreases according to the following equation;

v = u - g·t

Where;

v = The final velocity

g = The acceleration due to gravity = 9.81 m/s²

t = The time taken

Therefore whereby, the kinetic energy. K.E. is given by the equation , K.E. = 1/2 × m × u², as u reduces, the kinetic energy reduces

However, the potential energy, P.E. is given as P.E. = m × g × h

Where;

h = Height

m = The mass of the stone

Therefore, as the stone rises, the potential energy increases.

Linear expansivity is a property specific to a material and hence is constant.

Explanation:

Linear expansivity of the material will be constant irrespective of the shape and size of the material because it is a specific property.

It is a tendency of a material to expand in response to the increase in temperature.

The mathematical expression is given as:

where:

= change in temperature

L= initial length of the specimen

= linear expansivity

=change in length