Gravity: Compare Worlds and Scales

Distinguish gravitational weight, mass, and a scale reading.

All worksheets

5 questions0m 0s

Learn the skill

Use W = mg to compare gravitational forces. An ordinary scale senses the support force between itself and its load. At rest on level ground that support can equal weight; in free fall they need not match.

Worked example

A 2 kg object at g = 10 N/kg has weight 20 N. A supporting scale at rest reads a force of 20 N. If both fall freely together in an ideal model, the support force becomes zero, but gravity remains.

A book rests on a table. Equal-length arrows show gravity downward and table support upward. Neither force has disappeared.

Would you believe it?

A floating object in an orbiting spacecraft still has mass. Floating does not remove its resistance to a change in motion.

NASA: mass and weight

Question 1 A 4 kg object is at g = 5 N/kg. Its gravitational weight is what? 20 N 9 N 0.8 N

Question 2 A 3 kg object moves unchanged from one world to another. What remains the same? Gravitational weight in all fields Every scale reading Mass

Question 3 A scale and its load fall freely together. What does a zero support reading establish? The load has zero mass No supporting force from the scale in this ideal model No gravity anywhere

Question 4 A book rests on a table. Which forces balance on the book? Upward support and downward weight Two downward weights Gravity and no other force

Question 5 At fixed mass, local g doubles. What happens to gravitational weight? It halves It is unchanged It doubles

Review your work

0correct

Complete the questions to review each answer.

View dashboard