Chapter-03: Dynamics

After studying this unit, the students will be able to:

• Define momentum, force, inertia, friction and centripetal force.
• Solve problems using the equation Force = change in momentum / change in time.
• Explain the concept of force by practical examples of daily life.
• State Newton's laws of motion.
• Distinguish between mass and weight and solve problems using F=ma, and w=mg.
• Calculate tension and acceleration in a string during motion of bodies connected by the string and passing over frictionless pulley using second law of motion.
• State the law of conversation of momentum.
• Use the principle of conservation of momentum in the collision of two objects.
• Determine the velocity after collision of two objects using the law of conservation of momentum.
• Explain the effect of friction on the motion of a vehicle in the contect of tyre surface, road conditions including skidding, braking force.
• Demonstrate that rolling friction is much lesser than sliding friction.
• List various methods to reduce friction.
• Calculate centripetal force on a body moving in a circle using mv²

Multiple Choice Questions
1.	Laws of motion was presented by:
	a. Einstein	b. Newton
	c. Galileo	d. Archimedes
2.	Isaac Newton described the laws of motion in his famous book:
	a. Qanoon-ul-Masoodi	b. Principia Mathematica
	c. Kitab-ul-Astralab	d. Al-Manazir
3.	The laws of motion established the relationship between motion and ______:
	a. Force	b. Torque
	c. Acceleration	d. Momentum
4.	First law of motion is also known as law of _________:
	a. Torque	b. Acceleration
	c. Inertia	d. None of these
5.	_______ of a body is the direct measure of inertia:
	a. Mass	b. Energy
	c. Momentum	d. All of above
6.	The characteristic of a body due to which it tends to retain its state of rest or of uniform motion is known as:
	a. Weight	b. Force
	c. Inertia	d. Momentum
7.	______ is the agency which changes or tends to change the state of rest or of uniform motion of a body:
	a. Weight	b. Force
	c. Inertia	d. Momentum
8.	Law of inertia is actually the ______ law of motion:
	a. First	b. Second
	c. Third	d. Fourth
9.	When a force is applied on the body, _______ is produced in the body:
	a. Weight	b. Acceleration
	c. Energy	d. None of above
10.	The acceleration produced in a moving body is always in the direction of applied _______:
	a. Velocity	b. Force
	c. Speed	d. Momentum
11.	If mass of the body is doubled while keeping the force constant, then acceleration will be:
	a. One half	b. doubled
	c. One fourth	d. Four times
12.	If force applied on the body is doubled while keeping the mass constant, then acceleration will be:
	a. One half	b. doubled
	c. One fourth	d. Four times
13.	SI unit of force is:
	a. Kilogram	b. Dynes
	c. newton	d. Pound
14.	When a force of 8 newton is applied on a body of mass 2 kg, then the acceleration produced will be:
	a. 16 ms-2	b. 4 ms-2
	c. 0.4 ms-2	d. 160 ms-2
15.	1 N = ________:
	a. kgms-2	b. kgms-1
	c. kgm2s-1	d. kg2ms-2
16.	Action and reaction are equal hi magnitude but opposite in direction is known as ______ law of motion:
	a. First	b. Second
	c. Third	d. Fourth
17.	Walking on road is an example of ______ law of motion:
	a. First	b. Second
	c. Third	d. Fourth
18.	When a block is lying on a smooth surface, its weight is balanced by:
	a. Mass	b. Momentum
	c. Inertia	d. Normal Reaction
19.	The weight of a body of mass 10 kg on earth will be ________:
	a. Mass	b. Force
	c. Velocity	d. Weight
20.	The _________ of a body always acting towards the center of the earth:
	a. Mass	b. Force
	c. Velocity	d. Weight
21.	Quantity of matter in a body:
	a. Mass	b. Force
	b. Velocity	d. Weight
22.	The Force with which earth attracts a body towards its centre is known as:
	a. Mass	b. Force
	c. Weight	d. Inertia
23.	The characteristic of a body which determines the magnitude of acceleration produced when a certain force acts upon it:
	a. Mass	b. Force
	b. Inertia	d. Weight
24.	Mass of the body is measured by:
	a. Free Fall Apparatus	b. Physical Balance
	c. Spring balance	d. All of above
25.	Weight of the body is measured by:
	a. Free Fall Apparatus	b. Physical Balance
	c. Spring balance	d. All of above
26.	Unit of weight is:
	a. kg	b. ms
	c. Nm	d. N
27.	_______ of a body remains same everywhere:
	a. Weight	b. Acceleration
	c. Velocity	d. Mass
28.	_______ of a body does not remains same everywhere:
	a. Weight	b. Inertia
	c. Mass	d. All of above
29.	The value of weight of a body of constant mass depends on:
	a. Inertia	b. Momentum
	c. Force	d. ‘g’
30.	Mass is a _____ quantity:
	a. Scalar	b. Vector
	c. Derived	d. Negative
31.	Weight is a ______ quantity:
	a. Scalar	b. Vector
	c. Derived	d. Negative
32.	When a block is hanging with the help of a rope then weight of the body is balanced by:
	a. Acceleration	b. Inertia
	c. Displacement	d. Tension
33.	There are _______ cases of motion of the body hanging with the help of rope:
	a. 1	b. 2
	c. 3	d. 4
34.	The tension produced when one body moves vertically and the other moves horizontally ________ as compared to the tension produced when both bodies move vertically:
	a. Half	b. One fourth
	c. Double	d. Four times
35.	Quantity of motion in a body is known as:
	a. Mass	b. Momentum
	c. Velocity	d. Acceleration
36.	Product of mass and velocity is known as:
	a. Force	b. Speed
	c. Momentum	d. Acceleration
37.	SI unit of Momentum is:
	a. Kgms-2	b. Ns
	c. Kgms-1	d. Both b & c
38.	Kgms-1 = ________
	a. N	b. J
	c. Ns	d. W
39.	Rate of change of momentum is equal to:
	a. Force	b. Velocity
	c. Acceleration	d. Impulse
40.	Direction of the rate of change of momentum is in the direction of:
	a. Acceleration	b. Momentum
	b. Velocity	d. Force
41.	The force which resists the motion of one surface on another surface is known as:
	a. Gravity	b. Friction
	c. Weight	d. Repulsion
42.	When object is at rest, the force of friction is known as _____ friction:
	a. Static	b. Limiting
	c. Kinetic	d. Dynamics
43.	The maximum value of static friction is known as ______ friction:
	a. Static	b. Limiting
	c. Kinetic	d. Dynamics
44.	When an object is in motion then the force of friction is known as ______ friction:
	a. Static	b. Limiting
	c. Kinetic	d. Dynamics
45.	Static friction is ______ than kinetic friction:
	a. Less	b. Quartered
	c. Greater	d. Equal
46.	Rolling friction is ______ than sliding friction:
	a. Less	b. Quartered
	c. Greater	d. Equal
47.	The coefficient of friction has ______ unit:
	a. Newton	b. Dynes
	c. No	d. Kilogram
48.	Friction of liquids is ______ than friction of solids:
	a. Less	b. Quartered
	c. Greater	d. Equal
49.	Coefficient of friction does not depend upon the _______ between two surfaces:
	a. Area of contact	b. Normal Reaction
	c. Weight	d. Roughness
50.	The rolling friction is about ______ times smaller than sliding friction:
	a. 10	b. 50
	c. 100	d. 1000
51.	Friction in the human joints is much reduced due to the presence of:
	a. Bones	b. Muscles
	c. Fluid	d. Gas
52.	Value of coefficient of friction (µk) depends upon:
	a. Nature of the surfaces	b. Area of contact
	c. Force	d. All of above
53.	The Rotation of water sprinkler is an example of _____ law of motion:
	a. First	b. Second
	c. Third	d. Fourth
54.	A spider web remains intact due to:
	a. Weight	b. Momentum
	c. Tension	d. None of these
55.	Momentum of a moving body depends upon its:
	a. Mass	b. Velocity
	c. Weight	d. Both a & b
56.	Motion of the rocket is an example of:
	a. First law of motion	b. Law of conservation of Momentum
	c. Law of conservation of Energy	d. Weight
57.	Value of coefficient of static friction (µs) is usually _______ than coefficient of kinetic friction (µk):
	a. Less	b. Quartered
	c. Greater	d. Equal
58.	When air is released from an inflated balloon, it shoots off is an example of:
	a. First law of motion	b. Law of conservation of Energy
	c. Weight	d. Law of conservation of Momentum
59.	Sliding friction is commonly converted into Rolling friction by the use of:
	a. Ball bearing	b. Oil
	c. Grease	d. Polish
60.	The front sides of high-speed vehicles, aeroplanes and ships are shaped wedge like to reduce:
	a. Weight	b. Pressure
	c. Speed	d. Friction

Online Taleem provides students good notes in your study that helps you to quickly review the key points in the material that you have read and clear your concept is an important part of academic success in school / college. It is also an effective learning strategy that intentionally identifying the important content for your desire course and professional practice. This will also help you in improving your comprehension of material and retention.