Mass and Weight

Mass and WeightMassis the measure of the amount of matter in an object. (Metric units: grams, kilograms)

Weightis the measure of the force of gravity on a given object. (Metric unit: Newton)

The mass of an object will remain the same from one location to another. The weight of an object will change from place to place if the gravitational attraction changes.

Formula:W=mgWeight is measured in newtons (1 newton = 1 kg m/sec2)Mass is measured in kilogramsGravity is a constant: 9.8m/sec2

Example:Find the weight of a 30 kg object on the earth.G: m=30kg g=9.8m/s2R: W=?E: W=mg

S: W=(30kg)(9.8m/s2)A: W=294NExample:Find the mass of a 40 newton object on the earth.G: W=40N g=9.8m/s2R: m=?E:

S:

A: m=4.08kg m= 40kgm/s29.8m/s2m=WgExample:Find the weight of a 30 kg object on the moon, the moons gravitational attraction is 1/6 of the earths gravitational pull. Find its weight.G: m=30kg g=9.8m/s2R: W=?E: W=mg

S:

A: W=49NW=1(9.8m/s2)(30kg)6W=1(294N)61. An object has a mass of 5.5 kilograms. Find its weight.2. A ball has a mass of 3 kilogram. Find its weight.3. A bag of groceries has a weight of 44 newtons. Find its mass in kg.

Exercises:4. An astronaut has a mass of 90 kg. Find his weight if he is in a flight simulator where the gravitational attraction has been reduced to 1/10 of the earths pull.

5. If an object has a mass of 36 kg, find its weight on earth and on the moon. the moons gravitational attraction is 1/6 of the earths gravitational pull.