18. a) The materials that are in contact. The two materials and the nature of their surfaces. ...
b) The force pushing the two surfaces together. Pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other.
19. the quantity of motion of a moving body, measured as a product of its mass and velocity.
20. According to Newton's third law of motion, action force is equal to reaction but acts on two different bodies and in opposite directions. When a horse pushes the ground, the ground reacts and exerts a force on the horse in the forward direction. This force is able to overcome friction force of the cart and it moves.
21. The mass of an object is a measure of the object's inertial property, or the amount of matter it contains. The weight of an object is a measure of the force exerted on the object by gravity, or the force needed to support it. The pull of gravity on the earth gives an object a downward acceleration of about 9.8 m/s2.
22. R12. Mass is more fundamental because it is an intrinsic property of an object. Weight varies with location depending upon the acceleration due to gravity eg. for a mass m = 10kg on Earth it`s weight is W = mg = 10 x 10 = 100N.
The answer is c i have a 3 button mouse C.
The pH of a solution that has a H⁺ ion concentration is 0.0039M is 2.4.
<h3>What is pH?</h3>
pH of any solution gives idea about the acidity or basicity of solution and it will be calculated as:
pH = -log[H⁺]
Given that, concentration of H⁺ ion = 0.0039 M
On putting tis value in pH equation, we get
pH = -log(0.0039)
pH = -(-2.4) = 2.4
Hence required value of pH is 2.4.
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A. plate tectonics slowly move in what is called Continental Drift, the Earth used to be one continent called Pangea and has shifted ever since.
