Motion And Forces Flashcards
What is speed (m/s)?
The distance travelled by an object in a certain time
Equation for speed
Speed(m/s)= distance(m) divided by time(s)
What is velocity?
Speed with a direction
What is acceleration(m/ssquared)
Acceleration tells us how quickly an object changes speed. It’s a vector so has a size and a direction. Negative acceleration is called deceleration.
Equation for acceleration
Acceleration(m/ssquared)= change in velocity(m/s) divided by time(s)
What is Newton’s 2nd law?
Resultant force(N)= mass(kg) X acceleration(m/ssquared) For a constant mass, the larger the force applied to an object, the larger its acceleration For a constant force, the larger the mass of an object, the smaller its acceleration
What is thinking distance?
How far the car travels whilst drivers reactions are taking effect
What is braking distance?
How far the car travels under braking
Equation for stopping distance
Stopping distance= thinking distance + braking distance
What is Newton’s 1st law?
Inertia- an object in motion will remain in motion and an object at rest will remain at rest unless acted upon a force.
What will happen to the motion of a stationary object with zero resultant force?
The object will remain stationary
What will happen to the motion of a moving object with zero resultant force?
It’ll just carry on moving at the same velocity
What will happen to the motion of a non-zero resultant force acting on any object?
It will always produce acceleration (or deceleration) in the direction of the force. The arrows will be unequal.
What is Newton’s 3rd law?
For every action, there’s an equal but opposite reaction.
What is momentum?
Momentum is a property the all moving objects have. It can be thought of how difficult an object is to stop (the more momentum an object has the harder it will be to stop).
What does momentum depend on?
Mass
Speed (velocity)
Equation for momentum
Momentum(kgm/s)= mass(kg) X velocity(m/s)
What is the law of conservation of momentum?
States that the total momentum BEFORE an event (collision or explosion) equals the momentum AFTER the event.
What is Hooke’s law?
The extension of a stretched spring is directly proportional to the load of force applied
Equation for force
Force(N)= spring constant(N/M) X extension(m)
What is limit of proportionality?
There’s a limit to the amount of force you can apply to an object for the extension to keep on increasing proportionally. There is a maximum force above which the graph curves, showing that extension is no longer proportional to force. This is know as the limit of proportionality.
How does spring constant relate to stiffness of the spring?
The spring constant depends on the material that you are stretching- a stiffer spring has a greater spring constant.
What is mass?
Amount of matter (particles) in an object
What is weight?
A force (depends on objects’ mass and gravity of planet).
What is a resultant force?
The overall force on a point or object. If you have a number or forces acting in a single point, you can replace them with a single force (so long as the single force has the same effect as all the original forces together). This single force is called the resultant force.
What is terminal velocity?
Maximum top speed of an object. Occurs when forces are balanced and the resultant force is 0.
What forces act on a parachuter?
Weight and air resistance. Air resistance increases as you fall faster.
4 factors that affect thinking distance
Distractions-phone, passengers,food,radio
Fatigued
Alcohol/drugs/caffeine
Speed
7 Factors that affect braking distance
Mass of car Weather-ice/rain Condition of tyres Condition of brake pads Road surface Steepness of slope Speed
