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- Question
A boy sitting in a train moving with a uniform velocity drops a coin outside. A man standing outside the train will find the trajectory of the coin to be
Options- A. a parabola
- B. a circle
- C. a horizontal straight line
- D. a vertical straight line
- Correct Answer
- a parabola
ExplanationParabola, because when the coin is dropped at a particular point, it has the same velocity as the running train. So by Newton's first law, it continues its motion horizontally with that velocity. But then, it is also pulled down by earth's gravity continuously. In this situation its horizontal motion gives way to the parabolic motion until it reaches the ground.
- 1. Why does the sea appear blue in colour?
Options- A. Reflection of the sun light from water surface
- B. Interference of the sun light from water surface
- C. Scattering of the sunlight by water molecules
- D. refraction of the sun light Discuss
- 2. Heat is associated with
Options- A. K.E of random motion of molecules
- B. K.E of orderly motion of molecules
- C. Total K.E of random and orderly motion of molecules
- D. None of these Discuss
- 3. Parasec is ythe unit of
Options- A. distance
- B. time
- C. intensity of light
- D. magnetic line Discuss
- 4. What kind of crystalline solid is graphite?
Options- A. Metallic
- B. Ionic
- C. Molecular
- D. Covalent- network Discuss
- 5. What color does blue and yellow make?
Options- A. Green
- B. Black
- C. Red
- D. White Discuss
- 6. Max well is the unit of
Options- A. intensity of magnetization
- B. permeability
- C. magnetic flux
- D. magnetic susceptibility Discuss
- 7. A man stands in a lift which accelerates upwards. The resultant reaction force on the floor of the lift is
Options- A. greater than the weight of the man
- B. less than the weight of the man
- C. Same as the weight of the man
- D. Zero Discuss
- 8. What is unit of Viscosity ?
Options- A. coulomb
- B. newton second per square meter
- C. watt per meter per degree celcius
- D. joule per kilogram per Kelvin Discuss
- 9. What is unit of Astronomical distance ?
Options- A. light year
- B. angstrom
- C. weber
- D. lux Discuss
- 10. What is the minimum velocity required for a rocket to overcome earth's gravity and travel into space?
Options- A. 18 km/sec
- B. 11.2 km/sec
- C. 21 km/sec
- D. 35 km/sec Discuss
Physics problems
Search Results
Correct Answer: Scattering of the sunlight by water molecules
Explanation:
Sea appears blue in colour due to the scattering of the rays when they hit water molecules
Correct Answer: K.E of random motion of molecules
Correct Answer: distance
Correct Answer: Covalent- network
Explanation:
Graphite is a covalent-network type of crystalline solid.
There are two main categories of solids.
1. Crystalline solids and
2. Amorphous solids.
Crystalline solids are those in which the atoms, ions, or molecules that make up the solid exist in a regular, well-defined arrangement.
There are four types of crystalline solids :
Ionic solids :? Made up of positive and negative ions and held together by electrostatic attractions. They?re characterized by very high melting points and brittleness and are poor conductors in the solid state. An example of an ionic solid is table salt, NaCl.
Molecular solids :? Made up of atoms or molecules held together by London dispersion forces, dipole-dipole forces, or hydrogen bonds. Characterized by low melting points and flexibility and are poor conductors. An example of a molecular solid is sucrose.
Covalent-network (also called atomic) solids :? Made up of atoms connected by covalent bonds; the intermolecular forces are covalent bonds as well. Characterized as being very hard with very high melting points and being poor conductors. Examples of this type of solid are diamond and graphite, and the fullerenes. As you can see below, graphite has only 2-D hexagonal structure and therefore is not hard like diamond. The sheets of graphite are held together by only weak London forces!
Metallic solids :? Made up of metal atoms that are held together by metallic bonds. Characterized by high melting points, can range from soft and malleable to very hard, and are good conductors of electricity.
Correct Answer: Green
Correct Answer: magnetic flux
Correct Answer: greater than the weight of the man
Explanation:
The weight of the man mg is acting on the floor. As the lift is moving up with an acceleration, say a, the man too in it is having this acceleration. The force producing this acceleration is ma. By Newton's third law, this force will have an equal reaction pressing the floor equal to ma. Therefore the total resultant reaction on the floor is mg+ma = m(g+a) which is mg, the weight of the man. So (a) is correct.
Correct Answer: newton second per square meter
Explanation:
coulomb is unit of Electric Charge,
watt per meter per degree celcius is unit of Thermal Conductivity,
joule per kilogram per Kelvin is unit of Specific Heat capacity.
Correct Answer: light year
Explanation:
angstrom is used to measure wave length,
weber is used to measure Magnetic flux,
lux is used to measure Intensity of illumination.
Correct Answer: 11.2 km/sec
Explanation:
This 11.2 km/s is also known as the escape velocity. It works out to roughly 25000miles per hour
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