All 10 questions from the Post-UTME Screening (Post-UTME) Physics 2009 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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The nucleus of an atom is composed of
The atomic nucleus is made up of both protons and neutrons.
The half life of an element is 12hrs. If the initial mass is 50g. What mass will be left after 2 days?
2 days = 48 hours = 4 half-lives. Remaining mass = 50 x (1/2)^4 = 50/16 = 3.125g.
Which of the following statements is correct?
Gas pressure results from the collisions of gas molecules with the walls (and each other) of their container.
Determine the wavelength of the fundamental note of a guitar string of length 65cm long
For the fundamental mode of a string fixed at both ends, wavelength = 2 x length = 2 x 65 = 130cm.
Find the combined resistance of two wires each of resistance 8-ohms when they are connected in parallel
For two equal resistors in parallel: R = (8x8)/(8+8) = 64/16 = 4 ohms.
A force of 300N was used to pull a load of mass 40kg at a steady speed up an incline of length 6.2m and vertical height 3.5m. Determine the velocity ratio
Velocity ratio = distance moved by effort / distance moved by load = length of incline / height = 6.2/3.5 = 1.77.
Which of the following is NOT TRUE about pressure?
The correct SI unit of pressure is Nm^-2 (Pascal), not Nm^-1, making this the false statement.
120cm^3 of gas was collected at 20 degrees C and 745mm of mercury pressure. Find the volume of gas at standard temperature and pressure
V2 = 120 x (273/293) x (745/760) = 109.6cm^3.
A metal of length 30cm is heated until its temperature rises by 60 degrees C to a new length of 30.04cm. Calculate its linear expansivity
Linear expansivity = extension / (original length x temp change) = 0.04 / (30 x 60) = 2.22 x 10^-5 K^-1.
A magnetic needle is suspended first at earth's north magnetic pole and then at a point on the magnetic equator. The respective angles between the needle and the horizontal are
At the magnetic pole the needle points straight down (90° from horizontal); at the magnetic equator it lies horizontal (0°). This gives 90° and 0°, closest to option E (0° and 90°, order reversed) among those listed; the source key's stated answer (D: 90° and 60°) appears to be an error.
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