Chapter 5: Newton's Third Law (from Lecture Slide) Flashcards
Mass is most closely related to
Inertia
An object with a mass of 1 kilogram on Earth
Has the same mass on the Moon
A cart is pushed and undergoes a certain acceleration. If it were pushed with twice the force while its mass doubles, its acceleration would be
The same
Force and Interactions are between
One thing and another
Forces and Interactions are requires
A pair of forces acting on two objects
Interactions of hand and wall
Pushing on each other
Forces and Interactions equal in
Magnitude (Have the same strength) and opposite in direction and make up a single interactions
You cannot push the wall unless
It pushes back
Newton Third Law
Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force the first
To every action there is
Always an opposed equal reaction
Interaction
One thing interacts with another
Action-Earth (Object A) exerts
Force on ball (Object B)
Reaction-Ball (Object B) exerts
Force on Earth (Object A)
When you step off a curb, Earth pulls you downward and you pull Earth upward. Why do you not sense Earth moving upward toward you?
It moves, but by an unnoticeable amount. (primarily because the force exerted by Earth on you (due to gravity) is much greater than the force you exert on Earth.)
Why don’t equal and opposite forces cancel out?
Applied external force causes the to accelerate-Newton’s Second Law and only the action force
Action and reaction do not
Cancel because they act on different objects and external force by accelerating the object
The object is
No longer external to the system and the force pair is internal to the system which does not cause acceleration
Action and reaction within the system cancel with no external forces, there is
No acceleration of the system
The external force is
Friction between the object and its accelerates the system
The same force exerted on a small mass produces
A large acceleration
The same force exerted on a large mass produces
A small acceleration
When a cannon is fired, the accelerations of the cannon and cannonball are different because the:
Masses are different
When a bowling ball strikes a bowling pin, which imparts a greater force upon the other?
They impart equal force upon each other
When a bowling ball strikes a bowling pin, which experiences a greater acceleration?
Bowling pin.
Two people of equal mass on slippery object push off from each other. Will both move at the same speed in opposite direction?
Yes, but only if both push equally.
Vector components: Vertical and horizontal component of a vector are
Perpendicular to each other and determined by vector resolution
Resolving a vector into its components
V(x) and V(y) are the resolved components of the vector (V)
One person pulls on the sled on slippery as shown. Which components of her force F is greater?
The horizontal component F(x) is greater
As the ramp is raised, which force remains constant?
Mg
As the ramp is raised, how does the magnitude of N change?
N decreases with increases angle of the ramp
When the ramp is raised 90 degrees (vertical) what is the net force on block?
The net force is mg
When a surface is horizontal the normal force exerted by
The surface has the same magnitude as mg, the force due to gravity
Normal force decreases as
An incline increases
Mg is vertical and acts downward with only
A weight component pressing against the surface
The component of mg that acts
Opposite to the normal force (N) accounts for N being less on an incline
If the surface were vertical, acceleration would be a
Full g and it would be in free fall
Summary of Newton’s Laws
1) Newton First Law (The Law of Inertia)
2) Newton Second Law (The Law of Acceleration)
3) Newton Third Law (The Law of Interaction)
1) Newton First Law (The Law of Inertia)
An object at rest tends to remain at rest, an object in motion tends to remain in motion at constant speed along a straight-line path (F net = 0)
2) Newton Second Law (The Law of Acceleration)
When a net force acts on an object, the object will accelerate. The acceleration is directly proportional to the net force and inversely proportional to the mass (Fnet = ma)
3) Newton Third Law (The Law of Interaction)
Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first (F(a on b) = -F(b on a ))
