# Mass in metric, mass vs weight, law of motion, net force, vector

1. Answer the following:

a. What are the units of mass and the units of weight for the metric system?

b. What are the units of mass and the units of weight for the English system?

2. Explain the relationship between the mass and the weight of an object. Is the mass of an object the same on earth and the moon? Are the weights the same on earth and the moon?

3. In your own words, explain Newton's second law of motion and give two examples.

4. How does mass affect the rate of acceleration in free fall:

a. In air?

b. In a vacuum?

5. If the mass of a sliding block is tripled while a constant net force is applied, by how much does the acceleration decrease?

6. Explain the difference between a vector and a scalar quantity. Give at least two examples of different variables that are vector and scalar quantities.

7. Give and example of Newton's third law of motion and explain why it is an example.

8. For each of the following interactions, identify the action and reaction forces:

a. A hammer hits a nail.

b. Earth's gravity pulls down on a book.

c. A helicopter blade pushes air downward.

9. a. If you stand next to a wall on a frictionless skateboard and push the wall with a force of 30 newtons, how hard does the wall push on you?

b. If your mass is 60 kilograms, what is your acceleration?

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#### Solution Preview

Please find the solutions/explanations attached.

1. Answer the following:

a. What are the units of mass and the units of weight for the metric system?

Metric units for mass are grams, kilograms, milligrams, etc. Metric unit of weight is Newton.

b. What are the units of mass and the units of weight for the English system?

Units of mass for the English system are ounce, pound, ton etc. and unit of weight is pound-force.

2. Explain the relationship between the mass and the weight of an object. Is the mass of an object the same on earth and the moon? Are the weights the same on earth and the moon?

Weight W = mg, where m is the mass of an object and is g is the gravitational force.

The mass of an object remains same on earth and moon but there is difference in weights of an object on earth and the moon.

We know that gravity on moon is 1/6 of the gravity on earth.

Thus, the weight of an object on moon will be 1/6 of its weight on earth.

3. In your own words, explain ...

#### Solution Summary

The mass in metric, mass versus weight, law of motion, net force, vector and accelerations are examined.