P10(Force And Motion) Flashcards
What is Newton’s second law
The acceleration of an object is
-proportional to the resultant force on the object
-inversely proportional to the mass of the object
What is inertia
The tendency of an object to stay at rest to continue in uniform motion(moving at constant velocity)
The inertial mass of an object is …
A measure of the difficulty of changing the objects velocity
What’s the formula for inertial mass
What’s the formula for resultant force acting on an object
The greater the resultant force on an object…
The greater the objects acceleration
The greater the mass of an object …
The smaller it’s acceleration for a given force
The velocity of an object decreases if …
The resultant force is in the opposite direction to its velocity
What is the formula for momentum
P= mv
In a closed system…
The total momentum before an event is equal to the total momentum after the event
What’s the formula for the conservation of momentum
Ma X Va + Mb X Vb=0
What is the conservation of momentum
The total momentum before the event is equal to the total momentum after the event
The longer the impact time …
The more the impact force is reduced
When two vehicles collide …
-They exert equal and opposite forces on each other
-their total momentum is unchanged
What is the formula for impact force
Force= mass X change of velocity/ time taken
An object is elastic if …
It returns to its original shape when the forces deforming it are removed
What is hookes law
The extension of a spring is directly proportional to the force applied, as long as it’s limit of proportionality is not exceeded
What is terminal velocity
When an object moves at a steady speed in a constant direction because the
resultant force acting on it is zero
How is terminal velocity reached
-At the start the object accelerates downwards due to the force of gravity
-As the object’s speed increases frictional forces such as air resistance or drag increase
-At terminal velocity the weight of the object due to gravity is balanced by the frictional forces and the resultant force is zero
What are the forces on a parachutist
-when parachutist jumps they accelerate due to gravity
-as they accelerate drag increases therefore drag and gravity balance reaching terminal velocity
-they drop at constant speed
-parachute opens increased surface area causes drag to increase
-they decelerate
-eventually both gravity and drag balances reaching terminal velocity again but at much lower altitude
What does SUVAT stand for
S=distance
U=initial velocity
V=final velocity
A=acceleration
T=time
What is the stopping distance
The total distance travelled during the time it takes for a car to stop in response to some emergency
What is the formula for stopping distance
Stopping distance = Thinking distance + Braking distance
What is braking distance
the distance travelled under the braking force in metres
What is thinking distance
the distance travelled in the time it takes the driver to react
What is the 1 SUVAT equation
What is the 2nd SUVAT equation
What is the 3rd SUVAT equation
What is the 4th SUVAT equation
