Forces Flashcards
What is the SI unit that measures the strength of force
Newtons
What is a force
A push or pull
What is the overall force on an object called
Net force
What is and
Unbalanced force
A net force acting on an object
What can unbalanced forces called
Speed up
Slow down
Change direction
What is a balance force
Equal forces acting in opposite directions
What does a balanced force cause
Trick question
It will not change the objects motion
What happens when two forces act in the same direction
They add together
What is the net force when you add equal forces exerted in opposite directions
0
Describe how to combine unequal forces acting in opposite directions
You subtract the smaller force from the larger force. The direction of the resulting force is the direction of the larger original force
What is the difference between mass and weight
Mass- (kg) amount of matter in an object
Weight- (N) amount of force on an object due to gravity
Name the formula for calculating mass and weight on different planets like earth
Strength of gravitational field mass
Earth 9.8
Mass 50 kg
9.8x50=490(N) weight
What do we use to measure force
A Newton spring scale
What is the definition of friction
Friction is the force between two objects rubbing together
Name 2 ways forces are described
Strength
Direction in which they act
How does a cyclist reduce friction
Higher inflated tires
Smoother tires
Skinner tires
Less weight
Road condition
Give an example of kinetic energy into heat energy
Rubbing your hands together
What is the definition of streamlining
To reduce surface to surface resistance
What is the definition of minimizing surface contact
To reduce the rubbing area between two objects
What is the definition of lubrication
To apply wax, grease or oil to the rubbing surfaces between two objects
A toboggan slides down a hill. Is this work?
Yes
A weightlifter holds 200 kg mass motionless above his head. Is this work?
No because there is no movement being applied to the force.
You push on a car stuck in the snow. Is it work?
No because the car isn’t moving and you are pushing in the opposite direction as the force
In order for you to do work on an object what has to happen?
The object has to move some distance as a result of your force
The amount of work you do on an object depends on:
The amount of force you exert and the distance the object moves
What formula do you use to determine the amount of work done on an object?
Force x Distance
What is the SI unit of work
Newton x Meter
What is the amount of work you do when you exert a force of 1 Newton to move an object a distance of 1 meter?
1 joule
What is power?
Power is the rate at which work is done on an object.
Power equals the amount of work done on an object in a unit of time
example joules divided by second equals a watt
What is the formula used to calculate power?
Power= work divided by time
Watt= joules divided by time
What does the universal law of gravitation state ?
The force of gravity. Acts on all objects in the universe
what is the definition of gravity?
The force that accelerates objects towards earth
How does Oil between machine parts reduce friction?
It makes the surface smoother by changing from sliding friction to fluid friction.
What kind of friction occurs when moving parts have ball bearings?
Rolling friction
What kind of friction requires the most force to overcome, rolling friction ,sliding friction or fluid friction?
Sliding friction
Rolling friction
Fluid friction
Fluid friction occurs when
An object moves through a liquid or gas
Sliding friction occurs when
Solid surfaces slide over each other
Rolling friction occurs when
An Object rolls over a surface
Why does some fiction occur with seemingly smooth surfaces
The object is still being a rubbed against the surface. Therefore of force is still being applied
Give the definition of Air resistance
Air resistance is the kind of friction that slows a falling object
Give the definition of terminal velocity
A falling object reaches this when forces of gravity and air resistance are balanced
What is the definition of freefall
The state that exists when the only force acting on an object is gravity
Near the surface of Earth what is the acceleration of an object due to the force of gravity
9.8 m/s per second
An object that is thrown is called a
Projectile
What is the definition of work
A force that acts upon and objects to cause movement
Work = Work x distance
Give the definition of energy
Energy is a quantity that describes the amount of work that can be performed by a force
What are the different types of energy
Light heat sound Motion
What is the definition of potential energy
Potential energy is the stored energy of position possessed by an object
Give the definition of Kinetic energy
Kinetic energy is the energy of motion
What is the law of conservation of energy ,when was it made and what does it apply to
Energy can’t be created or destroyed
Energy can be transferred or transformed
19th century
Applies to any system
Mechanical advantage is the …..
Number of times a machine multiplies your effort force
What is the formula for mechanical advantage
Input force in newtons
F in
What is a machine
A machine is any mechanical system that reduces the force required to accomplish work
What is input force
Input force is the work done by you
What does a pulley do and what is the mechanical advantage
A fixed pulley only changes the direction between the input and output force
Mechanical advantage of one
