Question

Write answers to the following questions in your own words.
(a) Why is the weight of the same object different on different planets?
(b) What precautions will you take to make accurate measurements in day-to-day affairs?
(c) What is the difference between mass and weight?

Answer 1

(a) Weight of an object, W is given as W=mg

where m = mass of the object and g = acceleration due to the gravity of a place.

We know that acceleration due to gravity is different on different planets. Hence, the weight of the same object differs on different planets.

(b) Precautions to be taken to make accurate measurements in day-to-day affairs are

• The device used for measurement should be appropriate and properly working.
• The device should be used properly.
• It should be checked that the device in use should have stamp of standardization by the department of weights and measure.
• 3-4 readings should be taken for achieving accuracy in measurement

(c)

S. No.	Mass	Weight
1.	Mass is the amount of matter contained in a body.	Weight is the force exerted on a body due to the gravitational pull of another body such as Earth, the sun and the moon.
2.	Mass is an intrinsic property of a body.	Weight is an extrinsic property of a body.
3.	The mass of a body remains the same everywhere in the universe.	The weight of a body depends on the local acceleration due to gravity where it is placed.
4.	The mass of a body cannot be zero.	The weight of a body can be zero.
5.	The SI unit of mass is kilogram (kg).	Since weight is a force, its SI unit is newton (N).
6.	The mass of a body can be measured using a beam balance and a pan balance.	The weight of a body can be measured using a spring balance and a weighing machine.