2007 - WAEC Physics Past Questions and Answers - page 2
11
A swinging pendulum between the rest position and its maximum displacement possesses
A
Kinetic energy only
B
potential energy only
C
gravitational energy only
D
both kinetic and potential energy
correct option: d
Users' Answers & Comments12
A block of mass 4.0kg causes a spiral spring to extend by 0.16m from its unstretched position. The block is removed and another body of mass 0.50kg is hung from the same spiral spring. If the spring is then stretched and released, what is the angular frequency of the subsequent motion? [g = 10 ms -2]
A
10\(\sqrt 5\) rads-1
B
5\(\sqrt 2\) rads-1
C
5 rads-1
D
\(\sqrt 5\) rads-1
correct option: a
K = \(\frac{F}{e} = \frac{4}{0.16} = 250\)
F = \(\frac{1}{T} = \frac{1}{2 \pi \frac{\sqrt{m}}{k}}\)
= \(\frac{1}{2 pi \frac{\sqrt{0.5}}{250}}\)
= 10\(\sqrt{5}\)
Users' Answers & CommentsF = \(\frac{1}{T} = \frac{1}{2 \pi \frac{\sqrt{m}}{k}}\)
= \(\frac{1}{2 pi \frac{\sqrt{0.5}}{250}}\)
= 10\(\sqrt{5}\)
13
An external force of magnitude 100N acts on a particle of mass 0.15kg for 0.03s. Calculate the change in the speed of the particle
A
50ms-1
B
25ms-1
C
20ms-1
D
5ms-1
correct option: c
a = \(\frac{F}{m} = \frac{100}{0.15} = 666.7\)
v = u + at
= 0 + 66.7 x 0.03
= 20m/s2
Users' Answers & Commentsv = u + at
= 0 + 66.7 x 0.03
= 20m/s2
14
A car of mass 800kg moves from rest on a horizontal track and travels 60m in 20s with uniform acceleration. Assuming there were no frictional forces, calculate the accelerating force
A
240.0N
B
800.0N
C
1600.00N
D
2400.0N
correct option: a
S = at + \(\frac{1}{2} at^2\)
60 = 0 x 20 + \(\frac{1}{2}\) x a x 20
a = \(\frac{3}{10}\)m/s2
F = ma = 800 x \(\frac{3}{10} = 240N\)
Users' Answers & Comments60 = 0 x 20 + \(\frac{1}{2}\) x a x 20
a = \(\frac{3}{10}\)m/s2
F = ma = 800 x \(\frac{3}{10} = 240N\)
15
A plane inclined at 30o to the horizontal has an efficiency of 50%. Calculate the force parallel to the plane required to push a load of 120N uniformly upn the plane
A
50.0N
B
120.0N
C
200.0N
D
240N
correct option: b
V.R = \(\frac{1}{sin\theta} = \frac{1}{sin 30} = 2\)
M.A = \(\frac{E \times V.R}{100} = \frac{50 \times 2}{100} = 1\)
Effort = \(\frac{load}{M.A} = \frac{120}{1} = 120N\)
Users' Answers & CommentsM.A = \(\frac{E \times V.R}{100} = \frac{50 \times 2}{100} = 1\)
Effort = \(\frac{load}{M.A} = \frac{120}{1} = 120N\)
16
Mechanical energy can be either
A
kinetic or electric
B
chemical or potential
C
potential or kinetic
D
electric or heat
correct option: c
Users' Answers & Comments17
Which of the following surfaces will radiate heat energy best?
A
Red surface
B
white surface
C
black surface
D
yellow surface
correct option: c
Users' Answers & Comments18
The ice and steam point on a mercury-in-glass thermometer are 10cm and 30cm respectively. Calculate the temperature in decree Celsius when the mercury meniscus is the 14cm mark
A
20oC
B
30oC
C
34oC
D
70oC
correct option: a
\(\frac{x - 0}{100 - 0} = \frac{14 - 10}{30 - 10}\)
x = \(\frac{100 \times 4}{20} = 20^oC\)
Users' Answers & Commentsx = \(\frac{100 \times 4}{20} = 20^oC\)
19
Which of the following statements distinguishes thermal conduction for convection? i. Conduction requires a material medium while convection does not ii. In convection, there is actual motion of hot material, while in conduction, molecules molecules vibrates faster about their mean positions iii. Conduction takes place in solids while convection takes place in fluids.
A
i and ii only
B
ii and iii only
C
i and iii only
D
i, ii and iii
correct option: b
Users' Answers & Comments20
A cube made of metal of linear expansivity \(\alpha\) is heated through a temperature \(\theta\). If the initial volume of the cube is Vo, the correct expression for the increase in volume of the cube is
A
\(\frac{1}{3} \alpha V_o \theta\)
B
\(\frac{1}{2} \alpha V_o \theta\)
C
\(2 \alpha V_o \theta\)
D
\(3 \alpha V_o \theta\)
correct option: d
Users' Answers & Comments