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Physics Exercises - Force and Motion Exercises 1. An object experiences a net zero external unbalanced force. Is it possible for the object to be travelling with a non-zero velocity? If yes, state the conditions that must be placed on the object. Answer: Yes, it is possible. If an object is moving with a constant velocity in a straight line , the net external unbalanced force on it is zero. For this to happen, no external unbalanced force should act on the object. 2. When a carpet is beaten with a stick, dust comes out of it. Explain. Answer: When the carpet is beaten, it moves suddenly but the dust particles remain at rest due to inertia , so they separate from the carpet and fall down. 3. Why is it advised to tie any luggage ...

Cell Biology Questions and Answers Cell Biology Questions and Answers 1. Make a comparison and write down ways in which plant cells are different from animal cells. Plant cells have a cell wall, chloroplasts, and a large vacuole. Animal cells do not have a cell wall and chloroplasts and have small vacuoles. Plant cells can make their own food, but animal cells cannot. Plant cells are mostly rectangular, while animal cells are mostly round. 2. How is a prokaryotic cell different from a eukaryotic cell? Prokaryotic cells do not have a true nucleus, while eukaryotic cells have a proper nucleus with a membrane. Prokaryotic cells are smaller and simpler, while eukaryotic cells are larger and complex. Bacteria are prokaryotic, while plants and animals have eukaryotic cells with membrane-bound organelles. 3. What would happen if the plasma membrane ruptures or breaks down? ...

Class 9 Science: Motion - Exercises with Answers Class 9 Science Chapter: Motion - Exercises with Easy Answers Here are the detailed and simple explanations for your exercise questions from the chapter Motion to help you revise effectively. 1. An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes 20 s? Answer: Diameter = 200 m, so the circumference = π × 200 = 628 m (approx). Total time = 140 s. Number of rounds = 140 / 40 = 3.5 rounds. Distance covered = 3.5 × 628 = 2198 m (approx). Displacement after 3.5 rounds will be the diameter of the circle (since 0.5 round means opposite side) = 200 m. 2. Joseph jogs from one end A to the other end B of a straight 300 m road in 2 min 30 s and then turns around and jogs 100 m back to point C in another 1 min. What are Joseph's average speeds and velocities in jogging (a) from A to B and (b) from A to C? Answer: (a)...

Motion Class – 9th Standard Mode Motion Class – 9th Standard Mode An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes 20 s? Distance per lap = π × 200 m ≃ 628.3 m Total time = 2 min 20 s = 140 s ⇒ laps = 140 ÷ 40 = 3.5 Total distance = 3.5 × 628.3 ≃ 2199.1 m Displacement = straight‐line from start to end. After 3½ laps you’re opposite the start ⇒ 200 m Joseph jogs from A to B (300 m) in 2 min 30 s, then 100 m back to C in 1 min. Find average speed & velocity: a) A→B b) A→C a) A→B Distance = 300 m; Time = 150 s Speed = 300 ÷ 150 = 2.0 m/s Velocity = 300 ÷ 150 = 2.0 m/s b) A→C Total dista...

Class 9 Science - Tissues Exercises Class 9 Science - Tissues Exercises 1. Define the term “tissue”. A tissue is a group of similar cells that work together to perform a specific function in the body. 2. How many types of elements together make up the xylem tissue? Name them. Xylem is made up of four types of elements: tracheids, vessels, xylem fibres, and xylem parenchyma. 3. How are simple tissues different from complex tissues in plants? Simple tissues are made up of only one type of similar cells, while complex tissues are made up of different types of cells working together. 4. Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall. - Parenchyma: Thin cell walls. - Collenchyma: Thick at corners. - Sclerenchyma: Very thick and hard cell walls. 5. What are the functions of the stomata? Stomata help in the exchange of gases and in the process of tra...

Class 9 Science - Tissues Exercises Class 9 Science - Tissues Exercises 1. Define the term “tissue”. A tissue is a group of similar cells that work together to perform a specific function in the body. 2. How many types of elements together make up the xylem tissue? Name them. Xylem is made up of four types of elements: tracheids, vessels, xylem fibres, and xylem parenchyma. 3. How are simple tissues different from complex tissues in plants? Simple tissues are made up of only one type of similar cells, while complex tissues are made up of different types of cells working together. 4. Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall. - Parenchyma: Thin cell walls. - Collenchyma: Thick at corners. - Sclerenchyma: Very thick and hard cell walls. 5. What are the functions of the stomata? Stomata help in the exchange of gases and in the process of tra...

Class 9 Science: Structure of the Atom - Exercises with Answers Class 9 Science: Structure of the Atom - Exercises with Answers Exercises and Answers 1. Compare the properties of electrons, protons, and neutrons. Electrons: Negatively charged, mass 1/1836 of proton, revolve around nucleus. Protons: Positively charged, mass 1 unit, present in the nucleus. Neutrons: Neutral, mass equal to proton, present in the nucleus. 2. What are the limitations of J.J. Thomson's model of the atom? It could not explain the results of scattering experiments and the stability of the atom, and why electrons do not radiate energy while revolving. 3. What are the limitations of Rutherford's model of the atom? It could not explain the stability of the atom as revolving electrons should lose energy and fall into the nucleus. 4. Describe Bohr's model of the atom. Electrons revolve in fixed circular orbits called energy levels without radiating energy. Energy is absorbed or e...