Quick Matching (Newtons third Law)

Question

. 1. Match each of Newton’s laws to the situation which they best describe.

A. Newton’s first law B. Newton’s second law

C. Newton’s third law D. Law of universal gravitation

_____ The force that the Earth exerts on a group of astronauts gets progressively weaker as their rocket rises vertically upward.

_____ At all times the astronaut exerts as much force on the Earth as the Earth exerts on them.

_____ The rocket accelerates upward and the engines’ combined thrust overcomes gravity.

_____ Astronauts feel as though they’re being pushed back into their seats during launch

Answer 1

______The force that the Earth exerts on a group of astronauts gets progressively weaker as their rocket rises vertically upward.

Ans: D. Law of universal gravitation

Explanation: The Law of Universal Gravitation states that the force of gravity is inversely proportional to the distance squared: F = Gm₁m₂/r²

_____ At all times the astronaut exerts as much force on the Earth as the Earth exerts on them.

Ans: C. Newton’s third law

Explanation: Newton's 3rd Law states that for every force, there is an equal and opposite force. We push on the Earth and the Earth pushes back on us.

_____ The rocket accelerates upward and the engines’ combined thrust overcomes gravity.

Ans: B. Newton’s second law

Explanation: The acceleration is proportional to the force and the mass of the object.The force in this case is the thrust. The net force of the thrust is up, and therefore the rocket accelerates up.

_____ Astronauts feel as though they’re being pushed back into their seats during launch

Ans: A. Newton’s first law

Explanation: Newton's First Law is called "The Law of Inertia." Inertia is an object's ability to resist change in its motion (or lackthereof). In this case, the astronauts feel they are being pushed back because the rocket is accelerating and their bodies are resisting the change and only move when the rocket pushes them forward with itself.

Answer 2

Let's review these laws first:

The Newton's laws are: (1) Every object moves in a straight line unless acted upon by a force. (2) The acceleration of an object is directly proportional to the net force exerted and inversely proportional to the object's mass. (3) For every action, there is an equal and opposite reaction.

Newton's law of universal gravitation is usually stated as that every particle attracts every other particle in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

So, knowing these laws we can match the correct law with each sentence!

D The force that the Earth exerts on a group of astronauts gets progressively weaker as their rocket rises vertically upward.

__C___ At all times the astronaut exerts as much force on the Earth as the Earth exerts on them.

__B___ The rocket accelerates upward and the engines’ combined thrust overcomes gravity.

__A___ Astronauts feel as though they’re being pushed back into their seats during launch