Work done by conservative force is equal to
- A.Decrease in potential energy
- B.Increase in kinetic energy
- C.Increase in potential energy
- D.Decrease in kinetic energy
Correct answer
Explanation
The correct answer is A, Decrease in potential energy. A conservative force is one whose work depends only on the starting and the finishing point, not on the path taken, and whose work around any closed path is zero. Gravity and the spring force are the common examples. Potential energy is defined for such a force by the relation that the work it does equals the loss in potential energy. When a stone falls, gravity does positive work and the stone’s potential energy falls by exactly that amount. Option C is wrong because it states the opposite; potential energy rises only when work is done against the force, as in lifting the stone. Option B is right only when the conservative force is the sole force acting, so it is not the defining statement, and friction or an applied force would break it. Option D is wrong because kinetic energy grows, not falls, when such work is positive. Exam tip: conservative force, work equals minus the change in potential energy, and zero on a closed loop.
Practice Questions
View allThe fact that the planets move around the Sun, not in circles but in ellipses, was first demonstrated by
- A.Galileo
- B.Martin Luther
- C.Johannes Kepler
- D.Copernicus
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In 1609 Kepler showed that the planets move around the Sun in elliptical orbits, with the Sun at one focus of the ellipse.
Read the full explanation →Which one of the following statements is correct?
- A.Urea is produced in liver.
- B.Urea is produced in blood.
- C.Urea is produced from digestion of starch.
- D.Urea is produced in lung and kidney.
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Read the full explanation →Which one of the following is the correct sequence of passage of light in a compound microscope?
- A.Condenser-Objective lens-Eyepiece-Body tube
- B.Objective lens-Condenser-Body tube-Eyepiece
- C.Condenser-Objective lens-Body tube-Eyepiece
- D.Eyepiece-Objective lens-Body tube-Mirror
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Light passes through the condenser to the specimen, is picked up by the objective lens, travels up the body tube and reaches the eye through the eyepiece.
Read the full explanation →Which one of the following statements regarding haemoglobin is correct?
- A.Haemoglobin present in RBC can carry only oxygen but not carbon dioxide.
- B.Haemoglobin of RBC can carry both oxygen and carbon dioxide.
- C.Haemoglobin of RBC can carry only carbon dioxide.
- D.Haemoglobin is only used for blood clotting and not for carrying gases.
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Read the full explanation →Which one of the following statements regarding histone proteins is correct?
- A.Histones are proteins that are present in mitochondrial membrane.
- B.Histones are proteins that are present in nucleus in association with DNA.
- C.Histones are proteins associated with lipids in the cytosol.
- D.Histones are proteins associated with carbohydrates in the cytosol.
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They are the proteins around which DNA winds to form chromatin in the nucleus of eukaryotic cells. Histones are small basic proteins, rich in the positively charged amino acids lysine and arginine, which attract the negatively charged phosphate groups of DNA.
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