The common name is valve cover, so the correct answer is A.
Answer:
The direction of the contact forces acting on a body is not necessarily perpendicular to the contact surface. The resolution of contact forces in two components i.e. perpendicular to contact surface and along surface. Perpendicular component is normal force and parallel component is friction.
Explanation:
Answer:
2. A 1 litre mug of hot chocolate at 75 degrees.
Explanation:
Thermal energy is directly proportional to mass, so as the mass increases, the thermal energy of the substance increases as well.
The two forces of gravity are equal
Explanation:
We can answer this question by applying Newton's third law of motion, which states that:
"When an object A exerts a force (called action) on an object B, then object B exerts an equal and opposite force (called reaction) on object A"
In this problem, we can identify the Sun as object A and the Earth as object B. This means that the force of gravity exerted by the Sun on the Earth is the action, while the force of gravity exerted by the Earth on the Sun is the reaction: according to Newton's third law, these two forces are equal and opposite.
Therefore, the two forces of gravity are equal in magnitude, which is given by:

where
G is the gravitational constant
M is the mass of the Sun
m is the mass of the Earth
r is the separation between the Earth and the Sun
Learn more about Newton's third law:
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