1.3 Mass and weight

Mass:

Mass is a measure of the quantity of matter in an object at rest. (Mass is the amount of matter in an object)

Weight:

Weight is the force of gravity acting on an object that has mass. (Weight is a gravitational force)

W = mg

W = Weight (in Newtons)

m = Mass (Kg)

g = Gravity (on earth 9.8m/s^2)

The SI unit of weight is the same as that of force: the newton (N)

One newton is equal to 1 kilogram meter per second squared. 

$$One\;newton(1N)\;=\;Kgms^{-2}$$

Gravitational field strength

Gravitational field strength Defined as force per unit mass;

$$g={{W}\over{m}}$$

W = Weight (in Newtons)

m = Mass (Kg)

g = Gravity (on earth 9.8m/s^2)

Mass Vs. Weight

MassWeight
Mass always remains the sameWeight can change with location. 
Mass is measured in Kilograms, Grams etc.Weight is measured in Newtons (N)
Mass can never be zeroWeight can be zero
Mass has only magnitude (Scalar)Weight has both magnitude and direction (Vector)
Mass may be measured using an ordinary balanceWeight is measured using a spring balance.

The Greater the mass of a body, the greater is the inertia or resistance to change of motion

The weight of an object and its mass are directly proportional. For a given gravitational field strength, the greater the mass of the object, the greater its weight.

Good luck! Take your time and choose the best answer for each question.

Time's up! Let's see how you did.

1.3 Mass and Weight

QuizTest Your Knowledge

1 / 10

1.

A space rocket travels to the Moon.
The acceleration of free fall is greater on the Earth than it is on the Moon.
How do the mass and weight of the space rocket on the Moon compare with their values on the
Earth?

MCQ

2 / 10

2.

Two objects are placed on a balance, one on each side, as shown.

Two objects are placed on a balance, one on each side, as shown.

3 / 10

3.

A shopkeeper pours rice into a dish that hangs from a spring balance. He records the reading.

A customer buys some pasta. The shopkeeper notices that the reading on the spring balance,
with just pasta in the dish, is the same as it was with just rice in the dish.
Which quantity must be the same for the rice and for the pasta?

A customer buys some pasta. The shopkeeper notices that the reading on the spring balance, with just pasta in the dish, is the same as it was with just rice in the dish. Which quantity must be the same for the rice and for the pasta?

4 / 10

4.

Which statement about mass or weight is not correct?

5 / 10

5.

Two rectangular blocks consist of different materials.
Four different methods are suggested to compare the two masses.

  1. Compare the accelerations with which they fall freely.
  2. Compare the values of their lengths x breadths x heights.
  3. Hang each in turn from the same spring. Compare the extensions.
  4. Place one in the right-hand pan of a beam balance and the other in the left hand pan.
    Which methods give a comparison of the two masses?

6 / 10

6.

An object weighs 19 N on a planet where the acceleration of free fall is 3.8 m/s².
What is the mass of the object?

7 / 10

7.

An object is suspended from a spring balance on the Earth. The same object is suspended from the same spring balance on another planet.

Which statement explains the difference between the two readings?

An object is suspended from a spring balance on the Earth. The same object is suspended from the same spring balance on another planet.

8 / 10

8.

A person steps onto a bathroom scale.
The bathroom scale records both mass and weight.
Which row shows the readings on the bathroom scale?

A person steps onto a bathroom scale. The bathroom scale records both mass and weight. Which row shows the readings on the bathroom scale?

9 / 10

9.

A vehicle sent to explore the surface of Mars has a mass of 200 kg.
The acceleration of free fall on Mars is 3.7 m/s².
What is the weight of the vehicle on Mars?

10 / 10

10.

A student writes about mass and weight.
Which statement is correct?

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