Chapter 1 - Motion, Forces and Conservation of Energy Flashcards
(53 cards)
What is the difference between a vector and a scalar quantity?
A scalar measurement is just a magnitude but a vectors have a magnitude and a direction.
What is displacement?
The distance and direction from an object’s start point to it’s finish point.
What can you measure a vector direction as?
Relative to a point (e.g. towards the road) or as a bearing
What is the equation for speed (m/s)
Distance travelled (m)/Time (s)
What is uniform acceleration?
Accelerating/decelerating at a constant rate
What is the equation for acceleration (m/s^2)
(v-u)/t where v=final velocity, u=starting velocity and t=time
What is the equation for uniform acceleration?
v^2-u^2=2ax where v=final velocity, u=starting velocity, a=acceleration and x=distance
What does the gradient describe on a distance/time graph?
The speed of an object. Curves represent acceleration. A straight line means a constant speed
How do you work out the speed on a distance/time graph?
If it’s a straight line, the speed is equal to the gradient of the line but if it’s curved, then you draw a tangent and find the gradient of it (that only tells you the speed at that moment). For average speed, you simply do total distance travelled/time taken
What does the gradient describe on a velocity/time graph?
The acceleration of an object. A curve means it is an increasing/decreasing acceleration.
How do you work out the distance travelled on a velocity/time graph?
The area under any section of the graph is equal to the distance travelled in that time section
What is Newton’s First Law?
If the resultant force on a stationary object is zero, the object will remain stationary. If the resultant force on a moving object is zero, it will remain moving at the same velocity.
What is Newton’s Second Law?
Force = mass x acceleration. The resultant force and the acceleration of an object are directly proportional but the mass and acceleration of an object are inversely proportional
What is Newton’s Third Law?
When two objects interact, the forces they exert on each other are equal and opposite
What is the difference between weight and mass?
Mass is the amount of matter in an object and it will have the same value anywhere in the universe. Weight is the force acting on an object due to gravity and is measured in Newtons (N).
What is the equation for weight?
mass (kg) X Gravitational field strength (N/Kg)
What is centripetal force?
If an object is travelling at the same speed in a circle, the velocity is constantly changing and the resultant force acting towards the centre of a circle. The centripetal force is the force that keeps something moving in a circle.
What is inertia?
The tendency to keep moving with the same velocity. E.g. objects at rest stay at rest (Newton’s First Law)
What is the inertial mass of an object? How can it be calculated?
A measurement of how difficult it is to change the velocity of an object. It can be calculated using Newton’s Second Law
What is the equation for momentum
p=mXv where p=momentum (kg m/s), m=mass (kg) and v=velocity (m/s)
Is momentum a scalar or a vector quantity?
Vector - always include a direction
What is the Conservation of Momentum?
the fact that the total momentum before = the total momentum after
What is the equation for change in momentum?
F=(mv-mu)/t
Force(N) = change in momentum (Kg m/s)/Time (s)
What is the stopping distance of a car?
The distance covered between the driver first spotting a hazard and the vehicle coming to a complete stop.
Stopping distance = thinking distance + braking distance