Forced And Their Effects Flashcards
3 non Contact forces and how they work
Gravitational attraction- attraction between two objects with mass. Larger mass = larger attraction
Electrostatic attraction/ repulsion- larger charge gives greater force. Like charges repel , opposites attract
Magnetic attraction / repulsion- stronger magnet gives stronger field (greater force). Like poles repel, opposites attract
2 contact forces and how they work
Normal contact force- force perpendicular to plane of contact
Friction- surfaces that are rough cause friction when moved
Vector -
Scalar-
Vector- size and direction (weight, velocity, force , displacement )
Scalar- just size (mass, distance , speed)
In a scale drawing for force what does it mean if the arrows are equal length and opposite direction
Equal magnitude, forces cancel out, object is in equilibrium, travels at a constant velocity
In a vector force diagram what does it mean if the arrows smaller?
Force is smaller
Describe the forces acting on a sky diver and how they interact
1)initially there’s no air resistance so only force acting on him is weight.
2) as he falls and accelerates he increasss speed
3) this increases air resistance
4) resultant force decreases
5) eventually weight and air resistance become balanced so there’s no resultant force
6) finally no acceleration and terminal velocity is reached
Describe forces acting on a car and how they interact…
1)Initially there’s Low air resistance so thrust is only hindered by friction.
2)-air resistance increases, decreasing resultant force decreases
3) eventually car travels at terminal velocity (thrust is balanced by drag and friction so there’s no resultant force)
Describe forces acting on a car and how they interact…
1)Initially there’s Low air resistance so thrust is only hindered by friction.
2)-air resistance increases, decreasing resultant force decreases
3) eventually car travels at terminal velocity (thrust is balanced by drag and friction so there’s no resultant force)
When can rotation occur ?
-if an object is attached to a pivot point. It can rotate around but not move away from
-a force is applied on object (not towards the point)
-force is applied perpendicular to object ( it will move around the pivot in this direction)
Moment of a force (newton meters)=
Moment of a force (Nm)= force (N) X distance perpendicular to the direction of force (m)
Example of a moment?
Bike riding- pressing down your foot on the pedal , caused a moment about the pivot, turning the pedal arms
When does equilibrium occur in moments and pivots?
Sum of anticlockwise moments= sum of clockwise moments
What can gears change by rotation?
Speed , direction, force
What will happen to the speed, direction and force if the first gear(supplying the force) is connected to a second gear with fewer teeth ?
-second gear will turn faster
-with less force
-in opposite direction
What does lubrication do for gears?
Reduce friction so reduces unwanted energy transfer by heat. Therefore increasing efficiency
