Chapters 8-9 Flashcards
Who wrote Principia?
Newton
According to Newton’s law of universal gravitation, what happens to the gravitational force as the distance between two objects increases?
Decreases
Which of the following statements is true concerning friction?
Has direction opposite to motion
What is the force of kinetic friction if the normal force is 18 lb and the coefficient of kinetic friction is .31?
5.6 lb
What is the acceleration of an object with a mass of 10.5 kg if a 12 N force pushes the object horizontally across a surface? Neglect friction.
1.1 m/s^2
What force is necessary to make a 52 kg object accelerate at 1.1 m/s2^? Neglect friction.
57 N
Of the four fundamental forces, which holds the nucleus together?
Strong force
Of the four fundamental forces, which is the weakest?
Gravitational force
Of the fundamental forces which is the strongest?
Strong force
Of the four fundamental forces, which is the attraction between different masses?
Gravitational force
Completion:
A force is any …..?
Push or pull
The statement that everybody maintains its present velocity unless the body is acted upon by an external force is known as …..?
Inertia
For every action there is always an equal and opposite ……?
Reaction
The …… fundamental force can be a force of repulsion.
Electromagnetic force
A drawing that shows all of the forces acting on a body is called a(n) ……?
Free-body diagram
The force that is equal in magnitude but opposite in direction to the resultant and achieves equilibrium in a system is called the …..?
Equilibrant
When an object’s mass is at rest, it is called the object’s ….. mass.
Inertial mass
The laws of planetary motion were developed by ……?
Kepler
The first accurate value of G was calculated by ……
Cavendish
A body that is not accelerating is said to be in ….. equilibrium.
Translational
The process in which we can find the center of mass of an irregularly shaped object is called …..?
Multiple suspensions
True/False:
According to the (principle of transmissibility) a vector may be applied anywhere along its line of action without changing its effect.
True
Any object can be balanced on a sharp point positioned precisely beneath the object’s (center of gravity).
True
A body acts as if all of its mass were concentrated directly at its (center of gravity).
True
Force is (inversely) proportional to acceleration.
Directly
Mass is (directly) proportional to acceleration.
Inversely
A (Newton) is the force required to accelerate a mass of one kilogram at a rate of one meter per second squared.
True
For a typical combination of surfaces u(s) is (larger) in value than u(k).
True
The force a surface exerts perpendicularly against an object’s weight is called the (normal force).
True
When given an object’s weight, you can find its mass by (multiplying) its weight by the rate of acceleration due to gravity.
Dividing
(Forces) always occur in action-reaction pairs.
True
An object is (stable) if it’s center of mass falls outside its base of support.
Unstable
The force transmitted along a rope or other connector is called (net force).
Tension
Equations:
Newton’s second law of motion
F=ma
Universal law of gravitation
M1 • M2
F= G—————
r^2
Determines force of static friction
F(sf) = (u)s • F(N)
Short Answer:
Define friction
Friction may be defined as the resistance arising when an object moves through a medium or across a surface.
In your own words, state two of the four laws of kinetic friction.
2. Kinetic friction is separate from velocity.
Name three of the four ways to reduce friction.
- By reducing the roughness of the surface
- By lubricating the surfaces
- By using rollers, roller bearings, or ball bearings.
Define stable and unstable equilibrium.
Stable equilibrium- An object in stable equilibrium is not easily tipped over.
Unstable equilibrium- An object in unstable equilibrium is upset at the slightest disturbance.
If a 55 N force is required to move an object that weighs 93 N across a level surface at a constant speed, what is the coefficient of kinetic friction?
Do math then
How large a mass will 32 N accelerate at the same rate achieved by 13 N acting on 8.3 kg?
Set up proportion then
If a box weighing 536 N is pulled forward at constant speed by a force of 150. N at an angle of 37.0 degrees with the ground, what normal force does the supporting surface exert on the box?
Review ch.9 review problem #6.
A box weighing 87 lb is being pulled with a rope that exerts a force of 60. lb at an angle of 15 degrees with the horizontal. If the coefficient of kinetic friction is .35 what is the kinetic friction?
Look at ch. 9 review problem # 6
Calculate the gravitational force between two masses of 455 kg and 625 kg, that are separated by 0.150 meters.
Use formula on card
