ARMY PUBLIC SCHOOL GOLCONDA
PRACTISE QUESTIONS
1. Find the dimensional formula of the following
constants in each formula
a = At+Bt2+C F= bt+ct2 V=
at3 + bt + c P= ½ At2
+ Bt/2
2. Suppose that two objects attract each other with a
gravitational force of 16 units. If the distance between the two objects is
doubled, what is the new force of attraction between the two objects?
3. Find the net gravitational force on an object is placed at
the centre of the square due to four identical masses of each 1 kg are placed
at four vertices of square whose side is 1m in length.
4. A calorie is a unit of heat or energy
and it equals about 4.2 J where 1J = 1 kg m2 s –2 . Suppose we employ a system
of units in which the unit of mass equals α kg, the unit of length equals β m,
the unit of time is γ s. Show that a calorie has a magnitude 4.2 α–1 β –2 γ 2
in terms of the new units.
5. The length, breadth and thickness of
a rectangular sheet of metal are 4.234 m, 1.005 m, and 2.01 cm respectively.
Give the area and volume of the sheet to correct significant figures.
6. When two masses of 10 kg and 15 kg are separated by a
distance of 10 m find out a point between them where net G.F become zero.
7. Define the kepler laws of motion.
8. Define static and kinetic frictional forces and write the
expressions for them.
9. Which is easier push or pull explain
10. Calculate the engine power that is required to lift wight of
100*10³ kg of coal per hour from a mine which is 360 m deep . Take g =
10 ms-²
11. A boy having a mass of 40 kg runs up a flight of 50 steps , each step is
10 cm high and the boy crosses each step in 5 seconds .Calculate (a) Work
done (b) Power developed .Given g = 9.8 ms-² .
12. A ball is dropped from a height of 10 m. What is its velocity when it
hits the ground?
13. A bullet of mass 15 g has a speed of 400 m/s. What is its kinetic
energy ? The bullet strikes a thick target and is brought to rest in 2 cm, calculate the average net force acting on the
bullet. What happens to kinetic energy originally in the bullet?
14. Whenn loading a truck, a man lifts boxes of 100 N each through a
height of 1.5 m.
(a) How much work does he do in lifting one box ?
(b) How much energy is transferred when one box is lifted ?
(c) If the man lifts 4 boxes per minute, at what power is he working ? (g = 10 m s−2)
(a) How much work does he do in lifting one box ?
(b) How much energy is transferred when one box is lifted ?
(c) If the man lifts 4 boxes per minute, at what power is he working ? (g = 10 m s−2)
15. A 1 kg block collides with a horizontal light spring of force
constant 2 N/m. The block compresses the spring m from rest position. Assuming
that the coefficient of kinetic friction between the block and the horizontal
surface is 0.25. What was the speed of the block at the instant of collision.
16. A train travels at 60 m/s to the east with respect to the ground. A
businessman on the train runs at 5 m/s to the west with respect to the train.
Find the velocity of the man with respect to the ground.
17. A train is moving
in the west direction with a velocity 15m/s.A monkey runs on the roof of the
train against its motion with a velocity 5m/s with respect to train .Take the
motion along west as positive
5.Velocity of train relative to its driver
5.Velocity of train relative to its driver
18. At what distance apart would two equal masses of 150 kg need
to be placed for the force between
them to be 2.0 10–5 N?
19. Calculate the size of the gravitational pull of a sphere of
mass 10 kg on a mass 2.0 kg when
their centres are 200 mm apart.What is the force of the 2.0 kg mass on the 10
kg mass?
20. Find the resultanat force
and direction when two forces of 5N and 10N are acting on a same object
at angle of 450.
21. Draw velocity -
time graph for motion with
·
Negative constant acceleration
·
Positive
constant acceleration
·
uniform
acceleration
22. Draw position -
time graph for motion with
I.
Positive velocity ii. Negative
velocity iii. Zero velocity
II.
Positive acceleration iv. Zero acceleration
23. Draw position - time graphs of two objects
moving along a straight line when their relative velocity is (i) zero and (ii)
non - zero
24. Find the resultanat force
and direction when two forces of 4N and 3N are acting on a same object
perpendicular to each other.
25. The
ceiling of a long hall is 25 m high. What is the maximum horizontal distance
that a ball thrown with a speed of 40 m s–1 can go without hitting the ceiling
of the hall?
26. A cricketer
can throw a ball to a maximum horizontal distance of 100 m. How much high above
the ground can the cricketer throw the same ball?
27. A stone
tied to the end of a string 80 cm long is whirled in a horizontal circle with a
constant speed. If the stone makes 14 revolutions in 25 s, what is the
magnitude and direction of acceleration of the stone?
28. An
aircraft executes a horizontal loop of radius 1.00 km with a steady speed of
900 km/h. Compare its centripetal acceleration with the acceleration due to
gravity.
29. A
particle starts from the origin at t = 0 s with a velocity of 10 𝑗̂
𝑚/𝑠 and moves in the
x-y plane with a constant acceleration of (8.0𝑖̂+ 2.0𝑗̂)
𝑚𝑠 −2 a) At what time
is the x-coordinate of the particle 16 m? What is the y-coordinate of the
particle at that time? b) What is the speed of the particle at the time?
30. The bob
of a pendulum is released from a horizontal position. If the length of the
pendulum is 1.5 m, what is the speed with which the bob arrives at the
lowermost point, given that it dissipated 5% of its initial energy against air
resistance?
31. Two
billiard balls each of mass 0.05 kg moving in opposite directions with speed 6
ms –1 collide and rebound with the same speed. What is the impulse imparted to
each ball due to the other?
32. A person
trying to lose weight (dieter) lifts a 10 kg mass, one thousand times, to a
height of 0.5 m each time. Assume that the potential energy lost each time she
lowers the mass is dissipated. (a) How much work does she do against the
gravitational force? (b) Fat supplies 3.8 × 107 J of energy per kilogram which
is converted to mechanical energy with a 20% efficiency rate. How much fat will
the dieter use up?
33. A body
of mass 2 kg initially at rest moves under the action of an applied horizontal
force of 7 N on a table with coefficient of kinetic friction = 0.1. Compute the
work done by the applied force in 10 s, work done by friction in 10 s, work
done by the net force on the body in 10 s, change in kinetic energy of the body
in 10 s, and interpret your results
34. A
constant retarding force of 50 N is applied to a body of mass 20 kg moving
initially with a speed of 15 ms–1 . How long does the body take to stop?
35. A
constant force acting on a body of mass 3.0 kg changes its speed from 2.0 m s–1
to 3.5 m s–1 in 25 s. The direction of the motion of the body remains
unchanged. What is the magnitude and direction of the force?
36. A man of
mass 70 kg stands on a weighing scale in a lift which is moving a) upwards with
a uniform speed of 10 m s–1 , b) downwards with a uniform acceleration of 5 m
s–2 , c) upwards with a uniform acceleration of 5 m s–2 . What would be the
readings on the scale in each case? d) What would be the reading if the lift
mechanism failed and it hurtled down freely under gravity?
37. A body of mass 10kg is
acted upon by two perpendicular forces of magnitude 10N and 5N. Find the
magnitude and direction of the acceleration.
38. Write the expressions for
the following
a)
Maximum height b)
range c) time of flight d) kepler third law
e) escape velocity f) orbital velocity g)
work done by variable force
h) impulse i) K.E in terms of momentum
39. Find the percentage
errors in the following
a)
S= 10± 0.1 m t= 1 ± 0.1 s in velocity
b)
M= 25± 1 kg F= 20± 1 N in acceleration
c)
E= 100± 2 J M= 2 ± 0.1 kg h= 20 ± 1 m in
acceleration
d)
a = 10 ± 0.1 m/s2 t= 10 ± 0.1 s in velocity
40. derive the following
expressions
·
equations of motion by calculus method
·
projectile motion A) max height b) Time of flight c) range
·
potential energy stored in spring
·
final velocities in 1D elastic collision
·
banking of roads
·
mechanical energy is conserved in free fall object
·
conservation of momentum
·
variation in g due to altitude and depth
·
escape velocity
·
orbital velocity
·
work energy theorem by constant force and variable force
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