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- Question
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
- Correct Answer
- greater than the weight of the man
ExplanationThe 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.
- 1. Max well is the unit of
Options- A. intensity of magnetization
- B. permeability
- C. magnetic flux
- D. magnetic susceptibility Discuss
- 2. 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 Discuss
- 3. 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
- 4. 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
- 5. Parasec is ythe unit of
Options- A. distance
- B. time
- C. intensity of light
- D. magnetic line Discuss
- 6. 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
- 7. What is unit of Astronomical distance ?
Options- A. light year
- B. angstrom
- C. weber
- D. lux Discuss
- 8. 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
- 9. Frictional force acts in
Options- A. the same direction as the motion
- B. the opposite direction of the motion
- C. all the directions
- D. upward direction Discuss
- 10. Solids have definite shapes.This is because
Options- A. the forces of cohesion of the molecules within are very much less in them
- B. the forces of cohesion are very large
- C. the forces of adhesion are large
- D. the forces of adhesion are less Discuss
Physics problems
Search Results
Correct Answer: magnetic flux
Correct Answer: a parabola
Explanation:
Parabola, 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.
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: 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
Correct Answer: the opposite direction of the motion
Explanation:
It is to overcome this opposite frictional force , that we have to apply the needed force to make the body move
Correct Answer: the forces of cohesion are very large
Explanation:
Cohesion refers to attraction between molecules of the same kind while adhesion refers to attraction between different kinds of molecules
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