Answer:
A. It is always a positive force
Explanation:
Hooke's law describes the relation between an applied force and extension ability of an elastic material. The law states that provided the elastic limit, e, of a material is not exceeded, the force, F, applied is proportional to the extension, x, provided temperature is constant.
i.e F = - kx
where k is the constant of proportionality, and the minus sign implies that the force is a restoring force.
The applied force can either be compressing or stretching force.
The movement of the tectonic plates is caused by convection currents in Earth´s mantle.
Answer: A) convection currents in Earth´s mantle.
Change of a liquid to a gas
Answer:
271cm^2
Explanation:
volume 1= 15^3 =3375
temp. 1. = 20+273 = 293
temp. 2. = 50+273 = 353
volume 2 =?
According to Charles law
volume is proportional to temperature
v2 = v1 * t2 / t1
v2 = 3375 * 353 / 293
v2 = 4066cm^3
v = area * length
4066 = area * 15
area = 4066/15 = 271cm^2
