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Explanation:
Use Pythagorean theorem:
r² = x² + y²
r² = (-6.46 m)² + (-3.78 m)²
r = 7.48 m
(a). If the temperature of a substance is increased the density of it will also increased. The temperature is directly proportional to the density because the molecular activity of the substance will be affected by the temperature
(b).The mass of the substance doesn't at all. Because the amount of matter inside the substance cannot be affected by the temperature except that its water
Answer: 
Explanation:
We know that force acting on an object due to Earth's gravity on the surface is given by:

where g is the acceleration due to gravity, r would be radius of Earth, M is the mass of Earth and G is the gravitational constant.
It is given that at pole, g = 9.830 m/s² and r = 6371 km = 6371 × 10³ m



Hence, Earth's mass is 