Miscellaneous

What are the seven basic physical quantities? answerTemperature (K)Length (m)Luminous intensity (Cd)Mass (kg) Number of particles (moles)Time (s)Charge (C)

What is meant by the "half-life" of a radioactive substance? answerHalf-life is the time taken for half the number of a specific typeof radioactive nuclei to decay. It is constant.dN/dt = -kNtherefore by integration, N = Noe^(-kt)lnN = lnNo - ktlnNo - lnN = ktNow, when N = No/2, ln2 = kt½thus t½ = ln2/kwhere k is the decay constant, N is the number or mass of radioactive nuclei at time t, No is N at t=0.

What is a Tesla? answerA Tesla (T) is a unit of magnetic field strength.It is the magnetic field strength required to produce a force of 1 N on a charge of 1 coulombtravelling 1 m/s perpendicularly to the magntic field.

What are some useful equations concerning uniformly accelerating bodies? answer1. v = u + at2. v² = u² + 2as3. s = ut + ½ at²