Physics problems
- 1. Max well is the unit of
Options- A. intensity of magnetization
- B. permeability
- C. magnetic flux
- D. magnetic susceptibility Discuss
Correct Answer: magnetic flux
- 2. 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
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.
- 3. 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
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.
- 4. What is unit of Astronomical distance ?
Options- A. light year
- B. angstrom
- C. weber
- D. lux Discuss
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.
- 5. 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
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
- 6. 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
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
- 7. 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
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
- 8. A capillary tube is partially dipped vertically in a vessel containing water. Due to capillarity water rises in the tube. The height of water rise in the tube can be increased by
Options- A. decreasing the radius of the capillary tube
- B. increasing the radius of the capillary tube
- C. increasing the height of water in the vessel
- D. None of these Discuss
Correct Answer: decreasing the radius of the capillary tube
Explanation:
The water rise in a capillary tube dipped in water is such that the weight of water in the tube above the surface of water in the vessel is equal to the upward force due to surface tension. So it is clear that if the bore to the tube is decreased , the height of the water column in it must be greater.
- 9. The fact that two large ships travelling on close parallel courses in the same direction tend to move towards each other can be explained by
Options- A. Bernoulli's principle
- B. Magnetic properties of the ship's material
- C. Newton's third law of motion
- D. Earth's gravitational force Discuss
Correct Answer: Bernoulli's principle
Explanation:
The rapid flow of air between the two moving ships causes a reducton of pressure (Bernoulli's principle) , so they (the ships) are drawn closer together
- 10. The cover of a solar coker is made of glass because
Options- A. it absorbs sun's rays
- B. it reflects sun's rays
- C. it retains the heat inside by the green house effect
- D. it rediates heat better than metals Discuss
Correct Answer: it retains the heat inside by the green house effect
Explanation:
As the inside of the cooker is painted black, heat absorption is more producing heat waves of longer wavelength which cannot escape through glass and hence are trapped inside. Thus the food is cooked.
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