Flashcards in ⭐️Topic SP2 - Motion And Forces Deck (36)
What is acceleration?
How much velocity changes in a certain time
How do you work out the resultant force of two forces on an object?
You add them if in the same direction or subtract them if opposite direction
What does Newton’s first law state?
A moving object will continue to move at the same speed and direction unless acted upon by an external force
An object in motion stays in motion unless acted upon by an external force
What is centripetal force?
The resultant force that causes an object to change direction - so it moves in a circular path
Give examples of centripetal force?
Friction, tension (e.g. wires of a fairground ride) and gravity
What is mass? When does it change?
The amount of matter there is in an object. It only changes when the object itself changes
What is weight?
A measure of the pull of gravity there is on an object
What device can be used to measure weight?
A force meter as they have a spring which stretches as the force on it increases
What is gravitational field strength in earth?
9.8 N/kg but in calculations can be rounded to 10N/kg
How can you calculate weight?
Weight (N) = mass (kg) x gravitational field strength (N/kg)
What is Newton’s 2nd law?
Force N = mass kg x acceleration m/s squared
What is the inertial mass of an object?
The force on the object / the acceleration produced by the force
What’s Newton’s third law?
Action reaction forces
Give characteristics of a pair of action reaction forces
They both are the same size
both act in opposite directions
They are the same type of force
What’s the difference between action reaction forces and balanced forces?
Action reaction forces act on different objects but balanced forces all act on the same object
What is momentum?
A measure in the tendency of an object to keep moving or how hard it is to stop it moving
Is momentum a vector or scalar?
How do you calculate momentum?
Momentum (kg m/s)= mass (kg) x velocity (m/s)
How can momentum and acceleration be combined in a formula?
F = m(v-u) / t
What is the rule for conservation of momentum?
When moving objects collide, total momentum of both objects is the same before the collision as it is after the collision as long as no external forces are acting upon it
What’s thinking distance?
The distance traveled by a driver while reacting to a situation
What’s breaking distance?
The distance travelled by the vehicle while the breaks are working to stop it
What’s stopping distance equal to?
Thinking distance + breaking distance
What is a reaction time?
The time between the person detecting their stimulus and their response
What can be used to measure response times?
Using computers or electric circuits
What’s the typical reaction time to a visual stimulus?
What increases reaction time?
By being under influence of drugs, alcohol or dit reactions like using your phone
What may increase the breaking distance?
By having worn out breaks as less friction is created, if the road is wet or there’s loose gravel as friction is reduced, if the tyres are worn out as friction is reduced, if the vehicle has a larger mass as more force is needed to decelerate it
Why is overall stopping distance for cars less than lorries
As cars will automatically have a smaller breaking distance as they have a lower mass