mechanics Flashcards
Distinguish between a vector and scalar?
A vector has magnitude and direction. A scalar has magnitude and no direction.
Which of the following are vector quantities?
Force, momentum.
Define velocity?
Velocity is speed in a given direction. It is the rate of change of displacement. Formula: v = s / t, where s = distance and t = time.
What quantity is defined as the rate of change of velocity?
Acceleration.
Define acceleration?
Acceleration is the rate of change of velocity. Formula: a = (v – u) / t, where u = initial velocity, v = final velocity, and t = time in seconds.
Define displacement?
Displacement is distance in a given direction. It is a vector.
What is work (Joule)?
Work is done when a force moves a body through a distance (displacement). Work = Force × Displacement (W = F × s).
Name the SI unit of measurement defined as the work done when a Force of one newton moves its point of application one metre in the direction of the force. What quantity, other than work, is also measured using this unit?
Joule (J). Other quantities measured using this unit include kinetic energy, potential energy, and food energy.
Define power?
Power is the rate of doing work. Formula: P = E / t, where E = Energy and t = time in seconds.
Define the unit of power (the watt)?
One watt is one joule per second. Formula: P = E / t, where E = Energy and t = time in seconds.
Define mass?
Mass is the amount of matter in a body and a body’s ability to resist motion. Mass is a scalar.
Define weight (force due to gravity)?
Weight is the product of mass and acceleration due to gravity. Formula: W = mg, where m = mass and g = acceleration due to gravity. Weight is a vector.
Define force?
Force causes a mass to accelerate or changes a body’s motion or direction. Formula: F = ma, where m = mass and a = acceleration.
Define the unit of force, the newton?
One newton gives a mass of 1 kilogram an acceleration of 1 metre per second squared.
Define momentum?
Momentum is the product of mass and velocity. Formula: p = m × v.
State the principle of conservation of momentum?
In a closed system with no external force, the total momentum before is equal to the total momentum after. Formula: m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂.
Define potential energy?
Potential energy is energy due to position. Formula: E = mgh.
Define potential and kinetic energy?
Potential energy is energy due to position. Formula: E = mgh. Kinetic energy is energy due to motion. Formula: E = 1/2mv².
What is the relationship between the potential energy and the kinetic energy of an object falling freely?
Potential energy equals kinetic energy. Energy = mgh = 1/2mv².
State the principle of conservation of energy?
Energy is neither created nor destroyed, but can be converted from one form to another. Total energy is constant in a closed system.
State Newton’s first law of motion?
An object remains at constant velocity or speed in a straight line unless acted upon by an external force.
State Newton’s second law of motion?
The rate of change of momentum is proportional to the force applied and in the same direction as the applied force. Formula: F ∝ (mv - mu) / t.
State Newton’s third law of motion?
For every action, there is an equal and opposite reaction.
What is the relationship between G, the gravitational constant, and g, the acceleration due to gravity?
g = GM / r².
State Newton’s law of gravitation?
The force is proportional to the product of two masses and inversely proportional to the square of the distance between them. Formula: F = Gm₁m₂ / r².
