Forces Flashcards
What is acceleration?
Rate of change in velocity
Is acceleration a vector or scalar quantity?
Vector quantity. This means it has magnitude and direction
What do distance-time graphs tell us?
How far something has travelled in how much time
What does the gradient of a line on a distance-time graph tell us?
Speed of the object
What does a straight line indicate on a distance time graph?
The speed is constant
What does a flat line indicate on a distance time graph?
Object is stationary
What does a curved line upwards indicate on a distance time graph?
Speed is increasing/ acceleration
What does a curved line downards indicate on a distance time graph?
Speed is decreasing/ decelaration
How do you find speed of a curve?
Draw a tangent, then find speed of the tangent
What is the formula for gradient?
Change in distance/change in time
Where is distance in distance-time graphs?
On the Y axis
Where is time in distance-time graphs?
X axis
What do velocity time graphs show us?
How an object’s velocity changes over time
Where is velocity in the graph?
Y axis
Where is time in velocity-time graph
X axis
What is the formula for gradient?
Change in velocity/change in time
What does the gradient show us in a velocity-time graph?
Tells us about an object’s acceleration
What does a constant positive gradient tell us?
Constant acceleration
What does a constant negative gradient tell us?
Constant decelaration
What does a flat line tell us?
Velocity is constant
Steep curve
Rate of acceleration is increasing
How do we find distance travelled in a velocity-time graph?
We find the area under the line
What is a force
A force is a push, pull or a twist.
What is force measured in?
Newtons (N)
Are forces vector or scalar?
Forces are vector
What are the 2 groups of forces?
Contact and non-contact forces
What are contact forces?
Contact forces are those where the 2 objects are physically touching
What are non-contact forces?
Forces where objects do not have to be physically touching
What is Newton’s first law?
A resultant force is required to change the motion of an object
What is Newton’s second law?
Any non-zero resultant force acts on an object, then it will cause the object to accelerate
What is thinking distance?
The distance a car travels while the driver is reacting to an incident
What is braking distance?
The distance car travels while brakes are applied
What are some factors that affect braking distance?
Speed of vehicle
Road conditions
Weight of vehicle
Tire condition
Efficiency of braking system
What are some factors affecting thinking distance?
Human Variation
External influence
Driver fatigue
Distractions
Visual impairments
Car’s speed
What is terminal velocity?
When the object doesn’t accelerate any further. Terminal velocity is the maximum speed attainable by an object
What are the forces on an object that is at constant velocity?
They are balanced
What is the formula for pressure?
Pressure = Force/Area
What is pressure measured in?
Pascals
What are the units of pascal?
N/M^2
What are some applications of objects with high pressure?
Knifes, scissors and saws all need to have high pressure to easily cut through objects
What are some applications of objects with low pressure?
Skis, tires, feet of big animals and seat belts need to have low pressure so that we can have stability, comfort and safety.
What are two fundamentals about pressure in fluids?
a. Pressure increases with depth
b. Pressure acts equally in all directions
What is the point that an object rotates around called?
The pivot
What is the rotational effect of a force called?
It is called the moment
How do we calculate moments?
Moment = force x distance to pivot
What are moments measured in?
Nm or Ncm
What are the 2 directions a moment can cause an object to move in?
Clockwise and anti-clockwise
Clockwise moments =
Anti clockwise moments
