CBSE Class 9 - Physics - Work (Questions and Answers) #class9Science #WorkPowerEnergy #eduvictors

CBSE Class 9 - Physics - Work (Questions and Answers)

Q1: 2 Newton-metre is how many joules?

Answer: ∵ 1 Nm = 1J ∴ 2Nm = 2J

Q2: In the CGS system, what is the unit for Work?

Answer: erg

Class IX Science Term 1 MCQs (2021-22) (#cbseTerm1)(#class9Science)(#eduvictors)

Class IX Science Term 1 MCQs (2021-22)

Q1. Rusting of an article made up of iron is called

(a) corrosion and it is a physical as well as chemical change

(b) dissolution and it is a physical change

(c) corrosion and it is a chemical change

(d) dissolution and it is a chemical change

Gravitation 1 - Mark Questions (Solved) CBSE Class 9 - Physics (#class9Physics)(#Gravitation)(#eduvictors)

Gravitation 1 - Mark Questions (Solved) CBSE Class 9 - Physics

Q1: Who formulated the universal law of Gravitation?

Answer: Isaac Newton

Q2: What is free fall?

Answer: When an object falls from any height under the influence of gravitational force only, it is known as a free fall.

Q3: What is the value of gravitational constant G on the earth? Does the value G change on the moon?

Answer: The value of the gravitational constant on the earth is 6.67×10⁻¹¹ Nm²/kg². The value of G does not change (universal constant), it remains the same on the moon.

Q4: What will happen to the gravitation force between two bodies, if the mass of one body is doubled?

Answer: Gravitational force will double also.

CBSE Class 9 - Physics - Chapter Motion - Short Questions and Answers - Part-1 (#eduvictors)(#cbse)(#cbseclass9)

Chapter Motion: Class 9 - Physics - Short Questions and Answers - Part-1

Q1:  An object has moved through a distance. Can it have zero displacements? If yes, support your answer with an example.

Answer: Yes, even if an object has moved through a distance, it can have zero displacements. For example, an object after moving through a certain distance (say d), comes back to its starting position. In that case, the distance covered is 2d while displacement is zero.


Q2: Is displacement a scalar quantity?

Answer: No, displacement is a vector quantity because it has magnitude as well as direction.


Q3:  State whether the distance is a scalar or a vector quantity.

Answer: Distance is a scalar quantity; it has magnitude but no specific direction.

PHYSICS: IMPORTANT DISCOVERIES(#eduvictors)(#cbsenotes)

Physics: Important Discoveries

No.	Discovery	Scientist	Year
1.	Proton	Rutherford	1919
2.	Neutron	James Chadwick	1932
3.	Atom	John Dalton	1808
4.	Atomic Structure	Neil Bohr & Rutherford	1913
5.	Radioactivity	Henry Becquerel	1896
6.	Radium	Madam Curie	1898
7.	Raman Effect	CV. Raman	1928
8.	X-Rays	Roentgen	1895
9.	Photoelectric effect	Albert Einstein	1905
10.	Periodic table	Mendeleev	1888
11.	Nuclear Reactor	Anrico Fermi	1942
12.	Wireless Telegram	Marconi	1901
13.	Dynamite	Alfred Nobel	1867

CBSE Class 9 - Physics - Work, Power and Energy - Worksheet (#eduvictors)(#cbsenotes)

Class 9 - Physics 

Work, Power and Energy 

Worksheet

Fill in the blanks with suitable words.

1. Energy is the __________ to do work. Its S.I. unit is ________.


2. Work is force multiplied by ___________ in the direction of force.


3. If the angle between force and the displacement caused is acute then work is said to be ________.


4. If the angle between force and the displacement caused is obtuse, the work is said to be _______.


5. One joule of work is said to be done when a force of ______ displaces a body through a distance of ________ in its own direction.

CBSE Class 9 - Physics - Gravitation and Flotation (Solved Numerical Problems) (#cbsenotes)(#eduvictors)

CBSE Class 9 - Physics -Gravitation and Flotation (Solved Numerical Problems)

Questions:

1) Find the total thrust acting on the bottom surface of a tank 4m long, 2m broad and 2m deep when fully filled with water. The density of water= 10³ kg/m³.

2) The gravitational force between two objects is 100N. How should the distance between the objects be changed so that force between them becomes 50N?

3) If the distance between two masses be increased by a factor of 6, by what factor would the mass of one of them have to be altered to maintain the same gravitational force? Would this be an increase or decrease in the mass?

4) The value of ‘g’ on earth’s surface is 9.8 m/s². Suppose the earth suddenly shrinks to one-third of its present size without losing any mass. What is the value of ‘g’ on the surface of shrunk earth?

5) Two bodies of mass 1kg and 100kg respectively are dropped simultaneously from same height 4.9m in a vacuum. Calculate and compare their final velocities just before hitting the ground and the time interval in which they will hit the ground.

6) The ratio of gravitational force on Neptune to the gravitational force on earth is 9:8. Ramesh weighs 792N on earth. Calculate his weight on Neptune.

Class 9 - Science - CH8 - Motion #class9Science #class9Physics #eduvictors

Motion

NCERT Chapter Questions and Answers and other Q & A

Q1: An object has moved through a distance. Can it have zero displacements? If yes, support your answer with an example.

Answer: Yes an object can have zero displacements even though it has moved through a distance. It happens when the object moves back to its original position i.e. final position coincides with the starting position.

Example: Suppose an object travels from O to C and then comes back to its original position O.

Total distance traveled = actual path covered = OC + CO = 25 + 25 = 50m

Total displacement = shortest distance between final position and initial position = 0m

Q2: What do you mean by a body in rest?

Answer: A body is said to be at rest if it does not change its position with respect to a fixed point in its surroundings.

Q3: Are motion and rest absolute or relative? Explain with an example.

Answer: No these terms rest and motion are relative. For example, a person inside a car, carrying a ball in his hand will see the ball is at rest. While for another person, outside the car will see the ball is also moving.

Q4: What is meant by scalars and vectors?

Answer:

• Scalar Quantities: Quantities that require magnitudes only to specify them are called scalar quantities or scalars. Mass, length, time, temperature, angle, area, speed, distance, volume and density are examples of scalar quantities.
• Vector Quantities: Quantities that require both magnitudes and direction to specify them are called vector quantities or vectors. Displacement, velocity, force, momentum, weight etc. are examples of vectors.

Q5: A farmer moves along the boundary of a square field of side 10 m in 40 s. What will be the magnitude of displacement of the farmer at the end of 2 minutes 20 seconds?

Answer:
As shown in the figure, let us assume, that the farmer starts from A.
Given, that the length of each side = 10m
Distance covered in 1 lap = Perimeter of ABCD = 4 x 10 = 40m

Time is taken by farmer to cover 1 lap = the 40s
Speed of farmer = Distance ÷ Time Taken for one lap = 40/40s = 1m/s

Distance covered by farmer in 2min 20 secs = Speed x Time = 1 x 140s = 140m

Number of laps covered = 140 ÷ 40 = 3.5 laps.
⇒ After the 140s, the farmer will be at position C (i.e. 3 and ½ laps).

Displacement = AC = (AB² + BC²)^½                 (applying Pythagoras theorem)
                   = (100+100)^½ = 10√2 = 10 x 1.414 = 14.14m      .... (answer)

Question: Can you find out displacement, if the farmer starts from the mid-point of AB?

Note: Displacement is a vector quantity that measures the shortest distance (straight line) between the starting point and ending point, not taking the actual path travelled into account.