2018 - JAMB Physics Past Questions and Answers - page 5

Commission means a task or mission to accomplish.

Take note of the double ‘s’ and the double ‘m’. All other options are wrongly spelt

Mechanical Advantage, M.A Velocity Ration (V.R) × Efficiency

M.A  = 5 × 0.72

M.A  = 3.6

Initial momentum = (0.8) × (5)

 = 4.0kgms\(^{-1}\)

  Final momentum

  = (0.8) × (– 5)

 = – 4.0kgms\(^{-1}\)

  Impulse on ball

  = Change in momentum

 = 4.0 – (– 4.0)

  = 8.0.0kgms\(^{-1}\)

V. R = \(\frac{1}{Sinθ}\)

  m = 20kg

  V.R = \(\frac{1}{Sin 30 }\)

  = 2

  Efficiency = 75%

  Load = mg

  = 20 x 10 = 200N

  Efficiency = \(\frac{M.A}{V.R \times 100}\)

  75/100 = \(\frac{M.A}{2}\)

  M .A = 75 x \(\frac{2}{100}\)

  M. A = 1.5

  Since M. A. = \(\frac{\text{Force}}{\text{Load}}\)

  Force = 1.5 x 200

  = 87 N

Inertia is the property of a body by virtue of which it opposes any agency that attempts to put it in motion or, if it is moving, to change the magnitude or direction of its velocity. Inertia is a passive property and does not enable a body to do anything except oppose such active agents as forces and torques. A moving body keeps moving not because of its inertia but only because of the absence of a force to slow it down, change its course, or speed it up.

\(\frac{I}{V}\) = \(\frac{1}{f}\) – \(\frac{1}{u}\)

\(\frac{I}{V}\) = \(\frac{1}{10}\) – \(\frac{1}{20}\)

  = \(\frac{1}{20}\) V

  V = 20cm.

  M = \(\frac{V}{U}\)

  = \(\frac{20}{20}\)

  = 1