Physics Study Guide (Forces and the Laws of the Motion)
The change in the horizontal velocity of a 12-kg scooter is +0.5 m/s. What is the net horizontal force acting on it?
+6.0N
Which of the following situations describe inertia?
- A stationary object tends to resist being moved - A moving object tends to resist a change in speed - A moving object tends to resist a change in direction
Name the contact forces
- Applied, tension, friction, buoyancy, air resistance, normal
Describe the concept of field forces
- Field forces can be exerted by objects that are in physical contact - Field forces can be exerted by objects that are not in contact - There are four fundamental field forces
Describe a free-body diagram
- Force diagrams show force vectors as arrows - Forces exerted on the object are represented
Describe the concepts of force diagrams
- Force diagrams show force vectors as arrows. - Forces exerted on the object are represented. - Forces exerted by the object are represented.
What is true of kinetic friction?
- Kinetic friction is calculated by the equation Ff= u(x)Fn - Kinetic friction is exerted opposite the direction of motion - Kinetic friction is exerted opposite the direction of motion.
Describe an object in equilibrium?
- The object is at rest - The object is moving at constant velocity - The net external force on the object is zero
Name the field forces
- gravity - electrical - magnetic
The acceleration due to gravity...
- is caused by a field force - has a magnitude of 9.81 m/s² at Earth's surface. - Is represented by the symbol ag (g is smaller)
An object is at rest on an incline. The component of gravity action downward and along the incline on the object is described as Fgx= +8.0 N. Which axis is pointing up the incline?
-x-axis
How do you calculate a force when the other two forces are going in opposite directions?
1. Calculate net force along each axis 2. Use pythagorean theorem to calculate result and force 3. State direction
What are the four fundamental faces?
1. Gravity 2. Strong nuclear 3. Weak nuclear 4. Electromagnetic
Two books are lying next to each other on a library table. The force due to gravity on the first book is 9 N and on the second is 13 N. The gravitational force on the table itself is 125 N. The floor supports the table with an upward force of 147 N. In a free-body diagram of the table, how many contact forces and how many field forces should be represented?
3, 1
A force of 5 N and a force of 15 N acting on an object can produce the following net forces except
5N
What is the value of G?
6.67x10⁻¹¹
During a three part circus stunt, a clown holds a ball. The clown then tosses the ball upward. After releasing it, the ball is caught a few moments later from above by another clown in a trapeze. Which set of data could represent the stunt. The force due to gravity on the clown is 680 N.
700 N, 705 N, 680 N
Equilibrium
A state in which the net force on an object is zero
Air resistance
A type of friction
A force unit is defined as the product of a mass and a unit of...
Acceleration
What is 9.8m/s²
Acceleration due to gravity
In an action-reaction pair, the
Action force and the reaction force act on two different objects.
The normal force...
Acts perpendicular to a surface
Newton's frist law
An object at rest, and an object in motion continues in motion with velocity (constant speed in a straight line) unless the object experiences a new external force.
Two forces act on an object. The magnitude of the net force action on the object
Cannot be determined from the given information
A lubricant decreases kinetic friction between surfaces. The most likely reason it reduces kinetic friction is because the lubricant...
Changes the composition and qualities of the surfaces in contact.
For an object in contact with a given surface, the kinetic friction acting on the object...
Depends on the composition and qualities of the surfaces in contact.
In interactions of action-reaction pairs involving Earth and everyday
Earth has great inertia
A plank is inclines at angle 0, north of west. The direction of the normal force exerted by that plank on an object would be oriented at angle 0,
East of north
A student holds a 6-N block of wood from a spring balance in an express elevator that maintains constant velocity traveling between floors. A spring scale reading of 5.9 N indicated that the elevator is...
Ending an ascending trip
An action exerted on an object which may change the object's state of rest or motion defines...
Force
Units that measure weight are units of
Force
What shows force vectors as arrows?
Force diagrams
What are the units that measure weight?
Force unit, which is destined as the product of a mass unit and a unit of acceleration
Newton's third law
If two objects interact, the magnitude of the force exerted on object 1 by object 2 is equal to the magnitude of the force exerted on object 2 by object 1, and these two forces are opposite in direction. (Every action has an equal and opposite reaction)
What does air resistance due when velocity increases?
Increases
Force
Is an action exerted on an object which may change the object's state or rest of motion.
Which of the following is true of inertia?
It is described in Newton's first law of motion
What does N.F.L refer to?
It refers to the net force on an object. The net force is the vector sum of all forces acting on an object.
Static friction
Keeps and object from moving
Which friction is bigger?
Kinetic friction<max static friction
What does the effect of a force depend on?
Magnitude and direction. (Thus, force is a vector quantity)
What is a measure of inertia?
Mass
What is another way to calculate net force?
Mass x acceleration
What is the SI unit of force?
Newton (Kg∙m/s²)
Two dogs are tugging on a toy. One dog pulls with a horizontal force of 14 N due north. The other is pulling due east with a horizontal force of 14 N. What is the direction of the net force on the toy?
Northeast
Unit for G.F
N∙m²/kg²
Normal force
Only if it is resting on a surface. - Is a force that acts on an object, perpendicular to the surface - Not always equal to gravity - Gets smaller as incline increases
Kinetic friction
Resists an object in motion
Free-body diagrams
Show only the forces acting on a single object
Newton's second law
The acceleration of an object is directly proportional to the force exerted on the object and inversely proportional to the mass of the object. (Bigger mass, less acceleration)
A batter strikes a baseball with a bat. Identify an action-reaction pair and describe the forces exerted by each
The batter exerts a force on the bat; the bat exerts a force on the batter
When is the net force acting on a car zero?
The car maintains both its speed and direction
A truck and a car uniformly accelerate from rest to a velocity of 3.0 m/s in equal time intervals. The truck is ten times as massive as the car. Which of the following statements is correct.
The force on the truck is 10 times the force on the car
Gravitational force
The mutual force of attraction between particles of matter
Inertia
The tendency of an object to resist being moved, or, if it is already moving, to maintain a constant velocity.
When Fr (air resistance) = applied/gravitational force, E F= (0/) and velocity is
constant
Action/reaction pairs act on.....
different objects
Acceleration is not always...
equal (Mass affects it)
What does gravitational force depend on?
mass and distance
Field forces exist in...
pairs
Forces always act in...
pairs
What is the formula for finding the radius, gravitational force,Fg, or the mass ?
r=√(G)(m1)(m2)/Fg
Magnitude of Fg is a scaler called....
weight
A single force acting on an object is represented in a free-body diagram of the object by the following force vector. ↑. Which of the following force vectors represents a single force acting an the object that will bring the object into the equilibrium.
↓
The gravitational force exerted on an object would most likely be represented by which force vector?
↓
