Answer:
C. are often metals
and
D. have high conductivity
Bread is considered to be a heterogeneous mixture. It is a heterogeneous mixture because all of the components that are used to make the bread are physically separate.
Answer:
(a) 
(b) 
(c) 
Solution:
As per the question:
Mass of Earth, 
Mass of Moon, 
Mass of Sun, 
Distance between the earth and the moon, 
Distance between the earth and the sun, 
Distance between the sun and the moon, 
Now,
We know that the gravitational force between two bodies of mass m and m' separated by a distance 'r' is given y:
(1)
Now,
(a) The force exerted by the Sun on the Moon is given by eqn (1):



(b) The force exerted by the Earth on the Moon is given by eqn (1):



(c) The force exerted by the Sun on the Earth is given by eqn (1):



Answer:
0.09 m/s²
Explanation:
Acceleration: This can be defined as the rate of change of velocity.
The S.I unit of acceleration is m/s².
From the question, expression for acceleration is given as
F' = ma
Using Pythagoras Theory,
√(F₁²+F₂²) = ma................... Equation 1
Where F₁ = Force of the First person on the boulder, F₂ = Force of the Second person on the boulder, F' = resultant force acting on the boulder, m = mass of the boulder, a = acceleration of the boulder.
make a the subject of the equation
a = √(F₁²+F₂²) /m................ Equation 2
Given: m = 825 kg, F₁ = 64 N, F₂ = 38 N,
Substitute into equation 2
a = [√(64²+38²)]/825
a = {√(5540)}/825
a = 74.43/825
a = 0.09 m/s²