UNIT 6.2 NEWTON'S LAWS

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This topic covers the concepts of inertia, mass and weight and the relationship between them. The relationship between force, mass and acceleration is then developed. Newton’s laws of motion are used to explain the behaviour of objects moving through the air, and the concept of terminal speed.
Mr S Lee
Flashcards by Mr S Lee, updated more than 1 year ago
Mr S Lee
Created by Mr S Lee over 6 years ago
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Question Answer
Newtons first Law of motion (law of inertia) states that... An object continues in its state of rest, or uniform motion, unless acted upon by an external resultant force.
Resultant force Usually, more than one force is acting on an object, like in a ‘tug-of-war.' What’s the resultant force here? Resultant force = 24 N + 39 N acting to the left - 63 N acting to the right Therefore resultant force = 0N
What force is needed to accelerate a car with a mass of 1,500 kg at 5 m/s2? F = m x a F = 1,500 x 5 F = 7,500 N
Calculate the force required to accelerate a car of mass 1,300 kg when it accelerates from 0 to 26.6 m/s in 3.8 s a = (v-u) ÷ t a = (26.6 - 0) ÷ 3.8 a = 7 m/s2 F = m x a F = 1,300 x 7 F = 9,100 N
Newton's 3rd law states that 'for every action there is an opposite an equal reaction' or... ...in an interaction between 2 bodies (A and B) the force exerted by body A on body B is equal and opposite to the force exerted by body B on body A.
When a rifle is fired, how does the size of the force of the rifle on the bullet compare with the force of the bullet on the rifle? The forces are the same, equal and opposite.
How does the acceleration of the rifle compare with that of the bullet? Explain your answer. The rifle will recoil backwards with less acceleration because it has a larger mass. a = F ÷ m
Interpret the velocity-time graph for a cyclist at A. A. The force of thrust forwards is much greater than the frictional forces (road friction and air resistance) backwards, so the cyclist's velocity rapidly increases.
Interpret the velocity-time graph for a cyclist at B. B. As the cyclist's velocity increases, air resistance also increases, so the rate of acceleration starts to decrease.
Interpret the velocity-time graph for a cyclist at C. C. Air resistance increases until it EQUALS the forward force. Because the forward and backward forces are equal, the cyclist stops accelerating continues to move at a constant velocity. This is called the TERMINAL VELOCITY.
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