70m/s-30m/s is eqal to 40m/s. Divide 40 by 10 and you get 4. This would be the accleration of the car.
The gravitation field strength of Planet X is 10 times that of Earth's, as the object weight has increased 10 times. This is only possible if the planet is more massive or more dense (smaller diameter).
Therefore, the answer is C.
Answer:
The evaporation time gradually increased with the increase in surfactant concentration, i.e., from water to the concentration level of 0.005%. Furthermore, the evaporation time is significantly reduced, even lower than that of water containing relatively high concentrations from 0.01% to 0.1%.
Answer:

Explanation:
Given a material with temperature coefficient of resistance <em>c</em>, the equation that relates the resistance
at temperature
and the resistance
at temperature
is

We want to double our resistance, so
, thus having:

For this T must be:


which for our values means (with
, remember to write temperature in S.I., and that for silver
):
