Topic 2 - Motions And Forces Flashcards
What is the resultant force?
Total force that results from 2 or more forces acting upon a single object
How do you work out the resultant of two forces?
If forces are acting in same direction , ADD them.
If acting in opposite directions, SUBTRACT one from the other.
When do we say the forces are balanced?
When the resultant of all forces is zero
When do we say the forces are unbalanced?
If there is a non-resultant force on an object
What is Newton’s First Law of motion?
A moving object will continue to move at the same speed and direction unless an external force acts on it.
A stationary object will remain at rest unless an external force acts on it
How do balanced forces affect velocity?
Does not change the velocity of an object
How do unbalanced forces affect velocity?
Will change speed and or direction of an object
What is a centripetal force?
A force that causes an object to follow a circular path.
The force acts towards the center of the circle
What is Mass?
Quantity of matter there is in an object
Only changes if the object itself changes
What is weight?
Measured using force meter
A measure of the pull of gravity on an object
Depends on the strength of gravity
How is weight calculated?
Weight = mass x gravitational field strength
(N) (Kg) (N/Kg)
Weight
Mass x Gfs
What is the gravitational field strength on earth?
10 (N/Kg)
In Newton’s 2nd law, what does acceleration in the direction of a resultant force depend on?
- size of force = same mass {Bigger the force, bigger acceleration}
- Mass of the object = same force {more mass, smaller the acceleration}
How is a force calculated?
Force = mass x acceleration
(N) (Kg) (m/s squared)
What is the inertial mass of an object?
More force needed to change velocity on a massive object
The force on it / acceleration {force produces}
^
Divide
What is the method for Core Practical > Investigating Acceleration?
1) Prop up one end of ramp until the trolley can move on its own. Set up the light gates and the pulley + string.
2) Place a piece of card to the top of the trolley. Measure the length.
3) Find mass of trolley and record
4) Put mass on the end of string. Keep this mass same every time.
5) Release trolley and record the speed. Also record the time
6) Put a mass on top of the trolley and repeat Step 5.
7) Repeat Step 5 with different masses on the trolley
What is Newton’s Third Law?
It’s about forces on two different objects when they interact with each other.
What can this interaction happen?
When objects touch i.e when you sit on a chair
At a distance, such as the gravitational attraction between the Earth and Moon
What are action-reaction forces?
Pairs of forces on interacting objects
action-reaction forces are always the same size, in opposite directions and acting on different objects
What is the difference between action-reaction forces and balanced forces?
Action-reaction forces act on different objects
Balanced forces act on same object
What happens with action reaction forces and collisions?
The action reaction forces that occurs during the collisions are the same size
However, they don’t have the same effect on the two objects because the objects have different masses.
What is momentum?
A measure of the tendency of an object to keep moving
Or how hard it is to stop it from moving
How do you calculate momentum?
Momentum = mass x velocity
(Kg m/s) (Kg) (m/s)
How do you calculate force using velocity and mass?
Force = mass x change in velocity
———————————-
Time
Force = m x (V-U) V= final velocity
————- U= initial velocity
t
