Motion 2 Flashcards
What is friction?
The force that acts when one surface slides over another. It always opposes the motion - this means that if an object is trying to slide to the left, friction will always act to the right and vice versa.
Friction converts kinetic energy into heat.
What are the two types of friction?
Static friction
Dynamic friction
What is static friction?
Occurs when the two surfaces are trying to slide over each other.
What is dynamic friction?
Occurs when one of the surfaces is actually moving.
How would you test for the static friction and dynamic friction of an object?
- Find the mass of the block by placing it on an electronic balance
- Pull the block with the spring balance (newton-meter) until the block moves at a steady speed and record the reading on the Newton meter in the table below when it starts to move and when it is moving steadily.
- Set a 100g mass on the block and repeat step 2
- Continue adding 100g masses and taking measurements until you have completed the table.
What is Newtons 1st law?
In the absence of a resultant force an object will remain at rest or continue to move at a constant velocity I.e balanced forces do not produce acceleration.
What is Newton’s second law?
The acceleration of an object is directly proportional to the resultant force acting on it and inversely proportional to the mass of the object.
OR
The rate of change of momentum of a body is equal to and in the same direction as the resultant force acting in it.
What is Newton’s 3rd law?
If body A exerts a force on body B, there is an equal and opposite force exerted on A by B.
(Sometimes called the reaction force)
These pairs of forces are always the same type.
What experiment investigates how acceleration is related to resultant force?
Apparatus and set up:
(Check page 8 of notes)
Method:
Set up the light gates and data logger to measure acceleration.
Measure the mass of the trolly, keep this constant for a fair test.
Change the accelerating masses.
Release the trolly through the gate.
Record the acceleration for each accelerating mass.
Repeat and average the results.
What equation relates force and acceleration?
F = mxa (Force = mass x acceleration)
Note: F is the resultant or unbalanced force.
What experiment is used to show that ‘g’ is constant in the absence of other forces such as air resistance?
Guinea and feather experiment.
Apparatus:
(See p21 of notes)
Method:
A vacuum was created in a glass tube by means of a pump.
A feather and a gold coin placed inside the tube were dropped at the same time.
The two bodies, despite their very different weights, reached the base of the tube together.
What experiment allowed us to find ‘g’ using light gates?
Apparatus:
(See p23 of notes)
Method:
Connect a light gate to the data logger
Imput the parameters to be measured (acceleration)
Set the separation of the black and white sections of the picket fence
Drop the picket fence through the light gate and read the acceleration from the data logger
Repeat and average results
What is the calculation to find weight?
W = m x g (Weight = mass x gravity)
How is acceleration/deceleration calculated using mass?
. Force
acceleration = ———-
Mass
If it is decelerating write as negative value
What equation relates speed and acceleration?
. Final velocity - initial velocity
a = —————————————
. time
