Dynamics - Classwork - PY7

Write down the first Newton's law of motion. [2]

Mac and Tosh are arguing in the cafeteria. Mac says that if he flings the Jell-O with a greater speed it will have greater inertia. Tosh argues that inertia does not depend upon speed, but rather upon mass. Who do you agree with? Explain why. [2]

(Jell-O - type of dessert)

A 4 kg object is moving across a friction-free surface with a constant velocity of 2 m/s. Which one of the following horizontal forces is necessary to maintain this state of motion? [1]

• 0 N

• 8 N

• 2 N

• depends on the speed

If your mass is 65 kg, then what is your weight?

Show your FULL SOLUTION in the box below or send it via special assignment on Teams. [3]

What is gravitational acceleration? [2]

The Moon has its own gravitational acceleration. Since the Moon is smaller in size and less massive, its gravitational acceleration is also smaller, about 1/6 of the Earth's acceleration. Taking that into account, what is going to happen to your mass and your weight on Moon? [1]

• Both mass and weight are smaller.

• Both mass and weight are bigger

• Mass is bigger but weight is smaller

• Mass is smaller but weight is bigger.

• None of the above.

Draw a free-body diagram of yourself sitting in the chair. Comment on what is the effect of forces acting on you - refer to appropriate Newton's Law.

Send it via special assignment of Teams. This is an integral part of classwork. [4]

Calculate the net force acting on this object: [2]

Suppose that a sled is accelerating at a rate of 2 m/s². If the net force is tripled and the mass is halved, then what is the new acceleration of the sled?

Show/describe your thinking. [3]

Edwardo applies a 4.25 N rightward force to a 0.765 kg book to accelerate it across a tabletop. The coefficient of friction between the book and the tabletop is 0.410. Determine the acceleration of the book. [5]

Pro-tip: draw a free-body diagram first, and only then attempt to solve the problem.

Pro-tip #2: when in doubt, follow the methods of problem-solving we outlined in classes.

Send your work via assignment on Teams