Topic 2 - Motion And Forces COPY Flashcards
What is a vector quantity?
Vectors have magnitude and direction
Give examples of vector quantities.(6)
Forces, velocity, displacement, weight, acceleration, momentum, etc.
What are scalar quantities?
Scalar quantities only have magnitude and no direction.
Give example of scalar quantities. (6)
Speed, distance, mass, energy, temperature, time, etc.
What is displacement?
Displacement is a vector quantity which measures the distance and the direction in a straight line form the starting point to the finishing point.
How is velocity different from speed?
Velocity is speed in a given direction.
What is the formula for average speed?
Average speed (m/s)= distance (m) / time (s)
What does the gradient of a distance-time graph represent?
Speed of an object.
Recall typical speeds of these:
- Wind
- Sound in air
- Person walking
- Person running
- Cyclist
- Car driving through town
- Car driving on Motorway
- Train
- Wind - 6m/s
- Sound in the air - 340m/s
- Person walking - 1 m/s
- Person running - 3 m/s
- Cyclist- 5.5 m/s
- Car driving through town - 13 m/s
- Car on Motorway - 30 m/s
- Train - 45 m/s
List two equations to work out acceleration.
Acceleration (m/s2)= (V - U) / T (Secs)
v2 - u2 = 2 X a (m/s2) X x(metre)
What does a diagonal line (/) represent on a distance-time graph?
Moving slowly/quickly (depending on the gradient) at a constant speed.
How do you calculate speed or distance on a point on a curved line on a distance-time graph?
Draw tangent to the curve at the point.
Then calculate the gradient of the tangent
What is uniform acceleration also known as?
Constant acceleration
What does a -acceleration mean?
Deceleration
What does the flat along 0 for the time axis mean (velocity-time graph)?
Stationary
How do you work out acceleration from a velocity-time graph?
Acceleration = Gradient of velocity-time graph
What does a diagonal line mean on a velocity-time graph?
Constant acceleration
Why does a object moving in a circular motion have a changing velocity?
- When an object moves in a circle at a constant speed, its direction constantly changes.
- A change in direction causes a change in velocity - This is because velocity is a vector quantity – it has an associated direction as well as a magnitude.
- A change in velocity results in acceleration, so an object moving in a circle is accelerating even though its speed may be constant.
Why must there be a centripetal force for circular motion?
- An object will only accelerate if a resultant force acts on it.
- For an object moving in a circle, this resultant force is the centripetal force that acts towards the middle of the circle.
Formula for weight (N)
Weight (N) = Mass (kg) x gravitational field strength (n/kg)
What is weight measured in?
Newtons
Describe the relationship between the weight of a body and the gravitational field strength
- Weight is the result of gravity. The gravitational field strength of the Earth is 10 N/kg (ten newtons per kilogram).
- This means an object with a mass of 1kg would be attracted towards the centre of the Earth by a force of 10N.
- We feel forces like this as weight.
What is Newton’s second law?
The second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object.
This means that F = M x A
What is inertial mass?
The ratio of force over acceleration is called inertial mass.
Inertial mass is a measure of how difficult it is to change the velocity of an object.