P2- Forces Flashcards
What does a scalar have?
Scalar quantities only have a magnitude and do not have a direction.
What does a vectors have?
Vector quantities have both a magnitude and a direction.
Give examples of scalar quantities
Speed, distance, mass, time etc.
Give examples of vector quantities
Velocity, displacement, force, acceleration
What is the formula for speed
speed (m/s) = distance travelled (m ÷ time (s)
What is the formula for velocity?
velocity (m/s) = displacement ÷ time
What is acceleration?
The rate of change in velocity
What is negative acceleration often called?
deacceleration
What is the acceleration formula?
Acceleration (m/s²) = Change in velocity (m/s) ÷ time (s)
a=∆v÷t
What is the acceleration formula when time is not given?
(final velocity)² - (initial velocity)² = 2 x acceleration x displacement
v²-u²=2as
What does uniform acceleration mean?
When the acceleration is constant
How can you investigate the motion of a trolley on a ramp?
Set up a ramp with a trolley and have 3 light gates at equal distance from each other. The light gate will record the time when the trolley passes through it. The time taken between the gates can find the average speed on the ramp. Then use the formula of acceleration. This will show the acceleration on the ramp and final speed on the runway
In a distance-time graph what does each thing represent? flat line straight line gradient curve
flat line = stationary
straight line with gradient =Constant Speed
gradient = speed
curve = accelerating or decelerating
In velocity-time graphs what does each thing represent? flat line Uphill line Downhill line area under Curve Gradient
flat line = steady velocity Uphill line = acceleration Downhill line = acceleration area under = displacement Curve = changing acceleration Gradient = acceleration
To find velocity at certain point in the curve on the graph, what do we need to do?
Draw a tangent at that point, and use it to find the gradient of the line
What is a force?
A force is a push or pull that acts upon an object as a result of that object’s interactions with its surroundings.
What is force measured in?
Force is measured in Newtons (N), and has both a magnitude and a direction. Therefore, force is a vector quantity.
What is a contact force?
A contact force can only be exerted when objects are physically touching
What is a non-contact force?
A non-contact force can be exerted without objects physically touching
Give examples of contact forces.
Friction - object and surface touch
Air resistance - object has to be in contact with air
Tension
Normal contact force
Give examples of non- contact forces
Gravitational
Magnetic
Electrostatic
What is a free body diagram?
- Free body diagrams use arrows to show all of the forces acting on an object.
- The length of each arrow indicates the magnitude of that force.
- The direction of each arrow indicates the direction of the force.
What is resultant force?
The resultant force is the overall force acting on an object, taking into account all the different forces acting on it.
What does equilibrium mean?
All the forces acting on the object are balanced.
How do you use scale drawings to find the resultant force?
Draw the forces acting on the object to scale and ‘tip-to-tail’, then measure the length of the resultant force on the diagram. This is the line drawn from the start of the first force to the end of the last force
How do you resolve vectors?
- When you resolve a force, you split the forces into two forces perpendicular to each other. These have the same overall effect as the original one.
- You can use a scale diagram, so just draw two lines so that the original force becomes the longest side of a right-angled triangle
PRACTICE SCALE DRAWINGS AND RESOLVING VECTORS NOW!
I know you haven’t done it and you are going to skip this card, aren’t you? Silly person! This is for your education. NOW DO THEM!
What is Newton’s first law?
- If the stationary object has 0 resultant force, it remains stationary
- If there is a resultant force on a stationary object, it starts moving.
- If a moving object has 0 resultant force on it, it continues moving at a steady speed in the same direction
- if a moving object has a resultant force then it accelerates in the direction of the resultant force.