2012 NECO PHYSICS OBJECTIVE ANSWERS
PHYSICS THEORY ANSWERS
(1a) trajectory is the path that a moving object follow through space as a function of time.
(1b) v=8cms^-1=0.08,t=5s,g=10ms^-2, V^2=u^2+2as, S=(u+v)/2t, S=((0.08)/2)5= 0.2m.
(2a) moment of a force about a point is the product of the force and the perpendicular distance of its line of action from the point.
(ii) anticlockwise rotation must be equal to clockwise rotation.
(iii)clockwise moment must be equal to anticlockwise moment.
(3) block and tackle, inclined plane, lever, wheel and axle
(3b) draw the diagram.
(5) Magnification=5, f=20cm, v/f-1=M, (v/20)-1=5, v-20=100, v=120cm, M=V/u, 120/u=5, u=120/5=24cm
(9) decrease in mass= (0.15/100)*2.0=0.003, mass=0.000003kg, energy=mc^2, remaining mass=0.002-0.000003=1.997*10^14J.
(10a)ionization energy is the energy required to remove electrons from gaseous atoms or ions.
(10b)Alpha particles are positively charged while beta particles are negatively charged
(11a) scalar quantity is a quantity that has magnitude only.
(ii) contact force requires a connection between the interacting objects while force field does not require connection between the interacting objects while force field does not require connection.
(iii 0 contact force occurs over a short distance while force field occurs over a very large area of force.
(11b) draw the diagram.
(11c)equilibrant is a force equal to, but opposite of vector force, that force which balances other forces thus bringing an object into equilibrium
(ii) parallegram law of vector states that if two vector quantities are represented by two adjacent sides or a parallegram then the diagonal of parallelogram will be equal to the resultant of these two vectors.
(11d) M=50g=0.05Kg, r=0.4m, K=0.6Nm^-1, w=2 pie f, w=sqr rut(K/m), 2 pie f= sqr rut(0.06/0.05), 6.29f=3.46
(ii) w=2 pie f= 2*(22/7)*0.55=3.46m/s.
(iii) Energy= (mv^2)/r, v=wr, E=m(wr)^2= 0.05*(3.46)^2*0.4=0.24J.
(12a) Newton’s first law of motion states that a body will remain ay rest or in uniform motion on a straight line unless it is acted upon by a resultant force.
(12aii) Newton’s second law of motion states that the resultant force acting on a body is directly proportional to its rate of change in momentum.
Rate of change in momentum=(M(v-u))/t, recall that a =(v-u)/t, F=(m(v-t)/t)=ma, F=ma.
(12b) Energy is the ability to do work while power is the rate at which work done or energy is consumed.
(ii) principle of conservation of linear momentum states that when an object collides with another body, the total momentum before the collision is the same as the total momentum after collision, provided no external force is involved
(iii) when a swinging pendulum is moving and collides with another pendulum, it stops and the second pendulum begins to move and comes back and continues like that.
(iv) Mgh=1/2m(v)^2, 12*3*10=(1/2)*20*v^2, 360=10v^2, v^2=36, v= sqr rut(36)= 6m/s.
(13ai) wave is a disturbance or oscillation that travels through a medium from one location to another accompanied by a transfer of energy.