Topic 2 - Mechanics Flashcards
What is a vector quantity?
A quantity that has both size and direction e.g. acceleration, force, displacement.
What is a scalar quantity?
a quantity that has size only. e.g. volume, mass, temperature.
What is terminal velocity?
When the net force acting on a free-falling object becomes zero, and it no longer accelerates.
Newton’s 1st Law
An object at rest tends to stay at rest unless acted upon by an external unbalanced force. (or an object in motion tends to stay in motion)
/
If the net force acting on an object is zero, its velocity is unchanged
Newton’s 2nd Law
If there is an unbalanced force, then the object will accelerate in that direction.
Newton’s 3rd Law
Every action has an equal and opposite reaction
OR
If object A exerts a force on object B, then object B exerts an equal and opposite force on object A.
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.
What is Work?
work is the energy transferred to or from an object via the application of force along a displacement.. (the product of force and displacement)
Law of Conservation of Momentum
In a closed and isolated system, the total momentum of objects in the system before a collision is equal to the total momentum in the system after a collision.
Elastic Collision
A collision in which there is no net loss of kinetic energy in the system as a result of the collision. Both momentum and kinetic energy are conserved.
Inelastic Collision
A collision in which there is a loss of kinetic energy while the momentum is conserved. (occurs when 2 objects collide and do not bounce away from each other)
How to find the distance travelled from a velocity-time graph?
The distance travelled is represented by the area under the graph.
Formula for density
Mass/ Volume
What are the 2 equations that describe Newton’s second law of motion?
F = ma F= change in momentum/ change in time
“Air resistance is negligible…” means that?
There are no frictional forces.
When air resistance is negligible what does this mean for the forces acting on an object in parabolic motion?
When there is no friction during parabolic motion, the only force acting on the object is the gravitational force.
What does the equation Ep = (1/2) k (change in x)^2 show?
The equation shows us that the potential energy stored in a spring is proportional to the spring constant and to the square of the distance by which the spring has been compressed/
If two objects are fired with the same initial velocity and air resistance is negligible, what is their motion like?
Their motion will be identical
Motion only depends on the initial velocity
What happens to horizontal velocity when air resistance is negligible?
Horizontal velocity does not change.
Equation for work done involving kinetic energy?
Work done = final kinetic energy - initial kinetic energy.
What does the area under a force-time graph represent?
The change in momentum
What does the area under a force-displacement/ force-length graph represent?
Energy or work done
