Waec Gce 2017 Physics Obj And Theory Answers – Nov/Dec Expo

*2017 PRIVATE WASSCE PHYSICS   OBJ*

*1-10- ACBAABCABC*

*11-20- CADDCBABBA*

*21-30- CABADBCCCA*

*31-40- BAABCACACB*

*41-50- ABBACBADAB*

PHYSICS THEORY ANSWERS 

*Question one*

(a)  Horizontal speed just before it strikes floor = ucos(theta)

                                                                                    = 10cos0°

                                                                                    = 10 m/s

(b) t = √(2g/h)

        = √(2*10*1)

        = √20

        = 4.47s

Question 4

(a)  given: u = 20m/s

                   t = 4s

                   g = 10m/s²

                   h = ?

    Using s = ut - ½gt²

               s = 20(4) - ½(10)(4)²

               s = 0m

(b)   The inference is that after 4s, the ball returns back to the plane of projection

Question 3

Magnetic materials: ¶ Iron ¶ Cobalt ¶ Nickel

Question 2

¶ medical uses

¶ welding and cutting

¶ military uses for defense and counter measures

Question 5

The factors that determine the location of a solar power station are

¶ Intensity of sun light

¶ surface slope

¶ feeder capacity of the distribution center

8ai)

Force is a push or pull which changes a body state of rest or of uniform motion in a straight line

8aii)

The two types of force are

*constant force

*field force

*magnetic force

*gravitational force

=====

5)

i)availability of constant sunlight

ii)nearness to power grid

iii)must be closer to both skilled and unskilled labour

Question 11

(a)  ¶ Electrical method

       ¶ Contact method

(b)  Electric lines of force are imaginary lines drawn in an electric field in such a way that the direction at any point gives the direction of the electric field at such a point

(c)  QR = SP

(d)  Resistivity is the resistance of a unit length of material of unit cross-sectional area

(e)  Given: F = 50Hz

                   L = 10 mH (10×10^-³H)

       Inductive reactance, XL = 2πFL

                                                  = 2×3.14×50×10×10^-³

                                                  = 3..14 ohms

(f)  If voltmeter reads 12V, over the 500 ohms, then using I = V/R

                                                            current in the circuit is I = 12/500

                                                                                                     I = 0.024A

     Hence over the 200 ohms, V = IR

                                                    V = 0.024×200

                                                    V = 4.8 VOLTS

     Voltmeter will read 4.8 volts

 4a)

Time (t)=4secs

V=0ms^-1

pie call,V^2=U^2+2gh

O^2=20^2+2(-10)h

0=400-20h

20h/20=400/20

h=20m

4b)

the magnitude of the initial speed (u) is equal to the magnitude of the height attained

================================

6)

A P-type seme-coductor is an extresic semi conductor which has been diped with a trivalent impurity wheel holes are majority charge carries and electron are the majority charge carries

Question 8

a)(i) A force is anything that causes motion

(ii) ¶ contact force

      ¶ field force

b)(i)  Bodies are streamlined so they can overcome to a great extent the viscosity that exists in fluids

   (ii) ¶ submarines

         ¶ seals

8c

i) ¶ Fg is downwards

    ¶ T1 is upwards

ii) ¶ a = v²/r

       a = 7²/1.2

       a = 40.8 m/s²

    ¶ F = ma

          = 1.3 × 40.8

          = 53N

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