WAEC 2015: PHYSICS ANSWER

1a) Projectile is a body undergoing a motion under the combined effect of horizontal and vertical forces
1b) The horizontal components of the velocity remains the same because the body undergoes a uniform motion
2) Angle of projection(tita)=30degrees velocity(u)=150m/s At greatest height, v=0 t=Usin*tita/g t=(150*sin30degrees)/10 =150*0.5/10 t=7.5s
3) Given original lenght(Lo)=2.00m radius(r)=1.0mm=1*10^-3m Extension(e)=25mm=2*10^-3m Force(f)=10^3N stress =force/area Area(a)pie*R^2 =22/7*(10^-3)^2 3.142*10^16m^2 Stress=10^3/3.142*10^-6 =3.18*10^-1*10^3*10^6 =3.18*10^8Nm^-2 Strain=Extension/original length =25*10^-3/2 =1.25*10^-2 Young modulus(Y)=3.18*10^8/1.25*10^-2 Y-2.54*10^10Nm^-2
4) -By wind -By increasing the cup surface area -By reducing the temperature
7a) De brogile equation states that landa=h/mv where landa=wavelenght of light mv=p=momentum h=planck's constant
7b) The equation is used to explain the wave-nature of matter
12a)
Nucleon number is the sum of proton number
and neutron number
12b)
95=c+a
95=c+2
c=95-2
c=93
i)
Number of neutrons in americium-241 is
237-93=144
ii)
a=2, b=4, c=93
12ci)
Gamma ray is not deflected because it has no
charge
12cii)
-It has the highest penetrating power
-it has low ionizing power
12d)
N/Nt=(1/2)^t1/2/T
1/32=(1/2)^(110/t1/2)
5=110/t1/2
5t1/2=110
t1/2=110/5
t1/2=22s
t1/2=0.693/landa
22=0.693/landa
landa=0.693/22
landa=0.0315
landa=0.0315 per year


2015 waec PHYSICS answer
(1a)
Projectile is a body undergoing a motion under the combined effect of horizontal and vertical forces
(1b)
The horizontal components of the velocity remains the same because the body undergoes a uniform motion
==================================
(2)
Angle of projection(tita)=30degrees
velocity(u)=150m/s
At greatest height, v=0
t=Usin*tita/g
t=(150*sin30degrees)/10
=150*0.5/10
t=7.5s
=================================
(3)
Given original lenght(Lo)=2.00m
radius(r)=1.0mm=1*10^-3m
Extension(e)=25mm=2*10^-3m
Force(f)=10^3N
stress =force/area
Area(a)pie*R^2
=22/7*(10^-3)^2
3.142*10^16m^2
Stress=10^3/3.142*10^-6
=3.18*10^-1*10^3*10^6
=3.18*10^8Nm^-2
Strain=Extension/original length
=25*10^-3/2
=1.25*10^-2
Young modulus(Y)=3.18*10^8/1.25*10^-2
Y-2.54*10^10Nm^-2
=================================
(4)
-By wind
-By increasing the cup surface area
-By reducing the temperature
===================================
(7a)
De brogile equation states that
landa=h/mv
where landa=wavelenght of light
mv=p=momentum
h=planck's constant
(7b)
The equation is used to explain the wave-nature of matter
==============================
(8ai)
Uniform acceleration occurs when there is an equal changein n velocity with equal time interval no matter how small the time interval may be
(8aii)
V=wr
V=linear velocity
w=angular velocity
r=radius
(8b)
R= resultant
R=root(F1^2+F2^2)
R=root(30^2+40^2)
R=root(2500)
R=50N
(8c)
This is done to increase the surface friction in water
(8di)
Given;mass(m)=20kg
angle of inclineation(tita)=30degrees
F=UR
F=Umgcos*tita
ma*sin*tita=Umg cos tita
U=tan*tita
U=tan30
U=0.51
(8dii)
Frictional force(Fr)
Fr=Umgcos*tita
Fr=0.51*20*10*c0s30
Fr=90.9N
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