1) Give the importance on universal law of gravitation. Mass of an object is 50 kg What is it's
weight on earth? How they differ from each other?
2) A sphere of mass 40 kg is attracted by a second sphere of mass 15kg when their centres are 20cm
apart, with a force of 0.1mg weight. Calculate the value of gravitational constant.
3) a)A tuning fork having frequency 250HZ emits a wave which has a wavelength of 1.35m. Find the
speed of sound in air.
b) Give any three ways to reduce reverberation.
4) A ship which is stationary, is at a distance of 2800m from the sea bed. The ship sends an
ultrasound signal to the seabed and its echo is heard 4s. find the speed of sound in water.
5) An engine pulls a train 1km over a level track. Calculate the work done by the train given that
the frictional resistance is 10x10ʻN.
6) Find the energy in KWh consumed in 10 hours by 5 devices of power 500 W each.
7) Consider a free fall body and prove that mechanical energy is always conserved for any three
points (A,B,C). NB
8) Derive an expression for potential and kinetic energy of an object. N
9) A body of mass 5kg, initially at rest, is subjected to a force of 20N. What is the kinetic energy
acquired by the body at the end of 10s?
10) What are isotopes? Give its two applications.
11) An atom is electrically neutral. How can it become charged? Explain with the help of example.
12) Calculate the mass of a) one atom of oxygen b) one ion of oxygen
13) Draw the atomic structure of (i) an atom with same number of sub-atomic particles, (ii) an atom wi
same number of electrons in L and M shell.
Answers
1) Mass of you, mass of Earth, and the distance between the center's of gravity.
The mass of moon is 1/100 times and its radius 1/4 times that of earth. As a result, the gravitational attraction on the moon is about one sixth when compared to earth. Hence, the weight of an object on the moon is 1/6th its weight on the earth.
2) A sphere of mass 40 kg is attracted by a second sphere of mass 15 kg when their centers are 20 cm apart with a force of 0.1 milligram weight. Calculate the value of gravitational constant.
3) A tuning fork having frequency 256Hz emits a wave which has a wavelength of 1.35m. Find the speed of sound in air. Speed of sound in air, v=vλ=256×1.36=345.6m/s.
Thanks...
Answer:
ExplanationDistance (G)=20cm=0.2m
Mass (M
1
)=40kg Mass (m
2
)=15kg
Force (F)=0.1 milligram wt
=0.1×10
−3
×980 dyne
=98×10
−3
dyne
=98×10
−8
N
=9.8×10
−9
N
F=
R
2
GM
1
M
2
G=
M
1
M
2
Fk
2
=
40×15
9.8×10
−7
×0.2×0.2
=
4×15
98×2×2
×
10×10×10×10
10
−7
=6.5×10
−11
m
2
/kss
2