Newton's Law of Motion Flashcards
What is force? What is the symbol and in what units is it measured in?
A force is a push or a pull acting upon an object as a result of its interaction with another object. The symbol for force is F and it is measured in Newtons (N)
What is Newton’s first law? What does it state?
Inertia.
The Law of Inertia states that an object remains at rest or in constant motion in a straight line unless acted on upon by a net unbalanced force.
Why is an everyday object such as an apple stationary when placed on a table?
The apple is stationary because it has the force of gravity (also known as weight force) acting upon the object and pulling it down. However, there is another force equal in magnitude but opposite in direction pushing up on the object from the surface. Because these forces are equal in magnitude and are pushing upon each other, the apple has zero net force. Thus the apple is stationary because it doesn’t have any unbalanced forces acting on it and the force of gravity and force from the surface are balanced.
What is net force? What does zero net force mean?
Net force is the sum of all forces acting upon an object. Zero Net force means that the object HAS NO ACCELERATION (0 ACCELERATION). Zero net force means that an object is stationary or moving at a constant speed.
It is in a state of EQUILIBRIUM
Does zero net force mean that an object is stationary?
Yes, but it can also mean that the object is moving at a constant speed - since there is no acceleration and no forces acting upon it.
The larger the mass of an object, the more inertia it has. True / False?
True
If the net force of an object is zero, then…
The speed of the object is constant because there is no change in acceleration. The speed and direction DO NOT change.
When the net force is zero, the forces of an object are all balanced. True / False?
True
What is a force diagram?
A force diagram represents all the forces acting upon the object. The forces are drawn with arrowheads which show the direction of the force. The length of each line shows the size of each force.
What is a vector diagram?
A vector diagram shows the net force acting on an object, where all the forces are added together, showing the resultant force.
What is friction?
Friction is a force that resists the motion of one object against the other
What is Newton’s second law? What is the formula?
Newton’s second law states that the acceleration of an object is directly proportional to the net force and inversely proportional to the mass of the object.
Force = Mass x Acceleration
F = ma
a = f / m
What is the SI unit for mass?
Kg (Kilograms)
Thus, One Newton = Kg meters per second squared (since F = ma)
What is the difference in mass and weight?
Mass is the amount of matter in an object. But weight is the force of gravity acting upon the object.
Mass does not change in relation to location, but weight does. (such as in space or in a different planet)
What is the formula for weight?
Weight = Mass x Acceleration due to gravity
W = m x g
What is the formula for net force?
Net Force = Mass x acceleration
F(net) = m x a
Can acceleration occur without a change in speed?
Acceleration can occur when an object changes direction.
What is Newton’s third law?
Newton’s Third Law of motion states that whenever an object exerts a force on a second object, the second object exerts an equal and opposite force on the first.
Newtons third law of motion states that for every force in nature, there is an equal and opposite reaction
Determine the action and reaction force, when a filled up balloon is released.
The action force is the rubber of the balloon contracting and pushing the air backwards. The reaction force is the force of the air pushing forward on the inside of the balloon.
Do smaller masses have higher accelerations for the same force?
Yes, this is part of Newton’s Second Law of Motion
When do action reaction pairs balance out?
The action-reaction forces act on different objects.
Only forces acting on the same object can cancel out or balance. Therefore, when they act on the same object.
What is meant by an unbalanced force?
An unbalanced force is one that will cause an object to move with acceleration.
What can an unbalanced force cause?
If an object is at rest and an unbalanced force pushes or pulls the object, it can cause an object to change its motion. Unbalanced forces can also change the speed or direction of an object that is already in motion. This means that it could change the acceleration
What is the SI unit of weight?
Newtons
When there are vectors in opposite directions which are both equal in magnitude, they will both cancel out
factual
What is inertia by itself?
Inertia is a property of matter that causes it to resist changes in velocity (speed and direction)
Inertia is the tendency to resist change in motion
The acceleration and net force always act in the same direction.
True/False?
True
Is a ball towards the ground and bouncing back up an example of Newton’s Third Law? If so, why?
Yes, hitting a ball to the floor is an example of Newton’s third law of motion because the force exerted by the ball when hit on the floor is equal and opposite in the direction to the force exerted by a floor on the ball.
How can you calculate acceleration, given the original force, friction force and the mass? What would be the formula?
Using F =ma,
Acceleration = Force / Mass BUT because FRICTION IS INVOLVED,
it is now: (ORIGINAL FORCE - FRICTION FORCE) / MASS
(don’t forget to provide units)
Does the weight or mass change in space?
Mass will ALWAYS STAY THE SAME.
Only weight changes in space.
What are similarities and differences between action and reaction forces? Are they balanced?
Action and reaction forces are equal in magnitude but opposite in direction.
What are similarities and differences between action and reaction forces? Are they balanced?
Action and reaction forces are equal in magnitude but opposite in direction.
Do single forces exist? Or is there always one pair of force?
NO, SINGLE FORCES DO NOT EXIST.
forces always occur in pairs - the action and reaction forces
Is weight a force? Is it a vector quantity? What is its SI unit?
YES.
Weight is a force and it is a vector quantity. The SI unit for weight is Newtons
What does the h in Ep = m x g x h stand for?
H stands for the height of the object above the reference point in meters. This reference point is often the ground, which means how high the object is from the ground.
What is friction in terms of Newton’s first law?
Friction is a force that resists the motion of one object against the other. In terms of Newton’s first law, friction is an example of an ‘unbalanced force’ which has the capabilties of causing an object to slow down and thus change its speed
(Since Newtons first law states that an object will remain at rest or in constant motion in a straight line, unless acted upon by a net unbalanced force.)
Does net force use sign conventions?
YES.
if the right is positive and left is negative, the net force which is the sum of all the forces, would be (-x) + y + (-z) ….
Does net force use sign conventions?
YES.
if the right is positive and left is negative, the net force which is the sum of all the forces, would be (-x) + y + (-z) ….
