P8 - Forces In Balance Flashcards
What is a vector quantity?
A physical quantities with size(magnitude)AND direction.
What is a scalar quantity?
A physical quantity with size but no direction.
What is displacement?
Distance without a change in direction.
What is velocity?
Speed at a certain direction.
What is weight?
How much NEWTONS you weigh on a certain planet.
What is mass?
How much matter something has.
What is a force.
A push or a pull that acts on an object.
What is force measured in?
Newtons(N)
List the contact forces.
Friction
Tension
Air resistance
Thrust
List the non-contact forces.
Gravitational
Magnetic
Electrostatic
Nuclear
What is Newtons 1st law?
An object at rest remains at rest, and an object in motion remains in motion at constant speed.
What is Newtons 2nd law?
The acceleration of an object is directly proportional to the resultant force of the object but inversely proportional to the mass of the object.
What is Newtons 3rd law?
For every action there is an equal and opposite reaction. They are equal in magnitude.
What is friction?
Friction is the force exerted by a surface against an object when it moves across it.
What is the resultant force?
A single force that has the same effect as all the forces acting on an object.
What is Newton’s first law of motion?
If the resultant force acting on an object is zero, all the forces are said to be balanced.
- If the object is stationary, it will remain stationary .
- If the object is moving, it will continue to move at the same speed and in the same direction.
Name 3 vector quantities.
Acceleration
Velocity
Force
Weight
Displacment
Name 3 scalar quantities
Mass
Speed
Time
Distance
Energy
Power
How are vector quantities represented?
-Vectors can be represented by an arrow
- The direction of the arrow shows the direction of the vector.
- The length of the arrow shows the magnitude.
What is the definition of contact forces?
A force that occurs when objects are physically touching.
What is the definition of non-contact forces?
A force that occurs when objects are physically separated.
What does upthrust do?
The upward force acting on an object in a fluid, due to it experiencing a greater pressure below it than above it.
What does air resistance do?
It tries to stop things moving throught the air.
What does a reaction do?
It stops things going through solid objects - normal contact force.
What does thrust do?
Thrust is a force that pushes objects forward.
If the resultant force is zero what does it mean?
All the forces acting on the object are balanced.
Recall unbalanced forces.
If the resultant force acting on an object is not zero all the forces are said to be unbalanced. The speed of the object and the direction of motion may change.
What is terminal velocity?
The maximum velocity that an object can attain when it is falling through a fluid, such as air or water.
What are moments?
Moments are the turning force around a fixed pivot. It can act in a clockwise or anticlockwise motion .
What are ways to increase a moment?
Increasing the distance from the pivot (get a longer spanner). Increase the force applied.
What is the equation to find a moment?
Force(N) x perpendicular distance(m) = moment(Nm)
What is a lever?
A lever is a rigid body that is capable of lifting a heavy load with small effort. It is a force multiplier.
What are force multipliers?
Force multipliers multiply the applied foce, allowing you to lift more for less work - they increase the effect of a force.
How do you calculate gear ratio?
Number of teeth on the driven/number of teeth on the driver.
How do you calculate moments in gears?
Moment = Force x Gear radius
What is the gear called that turns the other gears- puts in the effort.
The driver
What are the gears called that are turned by the driver?
The driven.
What is the centre of mass of an object?
The centre of mass of an object is the point at which its mass can be thought of as being concentrated.
Describe how to find the centre of mass of regular shaped objects.
You would find the centre of mass by drawing lines from one corner to the parallel corner.
What is a plumb line used for?
A plumb line is used for finding the centre of mass of an irregular shaped object.
Explain how a plumb line is used on an irregular object to find the centre of mass.
- The irregular object is hanged freely, where the plumb line is attached underneath. The centre of mass is always below, in line with the thread. 2.Suspend the card attach the plumb line. Using a pencil and a ruler draw a line along the plumb line.
3.Repeat the last step from a different point. Centre of mass is where the lines cross.
State the principle of moments.
The sum of all the clockwise moments about any point = The sum of all anticlockwise moments about that point
What are the two possible scenarios for motion when the resultant force on an
object is zero?
Stationry or a constant velocity
How can you calculate resultant forces?
You can calculate resultant forces by using the parallelogram of forces.
How do you draw a parallelogram of forces.
Step 1: Work out a scale
Step 2: Copy out one force - The length needs to be drawn to scale.
Step 3: Measure the angle
Step 4: Draw the next
Step 5: Set your compass to the size of one of the forces.
Step 6: Place the compass point at the end of the other force and draw an arc.
Step 7: Set your compass to the size of the other force.
Step 8: Place the compass at the end of the other force and draw a second arc.
Step 9: Draw the resultant force from the ship to the point where the two arcs cross.
Step 10: Using a ruler measure the size of the resultant force.
Step 11: Calculate the size of the resultant force.
Give a detailed process of how to resolve forces in equilibrium.
1.First we can draw a geometric ‘scaled’ free
body diagram with our weight acting straight
down to ground.
2.Draw the force acting normal to the slope
and the force acting along side/parallel to
the slope to form parallelogram.
3.Measuring FN and FH will give use their
magnitude and we can also get their angle
easily.
