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# 4.8: Unit 4 Practice and Assessment

#### Outcome 1

1) Which has greater density between a kilogram of feathers and a kilogram of pennies? Which has greater volume? Which has greater mass?

#### Outcome 2

2) What is the weight in Newtons of a 3 kg textbook?

3) Convert your own weight from pounds to Newtons. Then calculate your mass in kilograms. Show all work.

4) The acceleration due to gravity (g) on the moon is 1/6 that on the surface of Earth. Based on your answers to the previous question, what would your weight be on the moon? What would your mass be on the moon?

#### Outcome 3

4) A 7 N force pushes on an object to the right and a 7 N force pushes on the object to the left. What is the net force? Can the object be in static equilibrium?

5) A 5 N force pushes on an object to the right and a 7 N force pushes on the object to the left. What is the net force? Can the object be in static equilibrium?

6) You push on a large box with 120 N of force, but it doesn’t move. How large is the friction force? Draw a free body diagram of the situation.

7) Helping a 48 lb toddler learn to float in a swimming pool you notice that it feels as though they only weigh 5 lbs. How large is the buoyant force on the toddler? Draw a free body diagram of the situation.

#### Outcome 4

8) What weight of water must the toddler in the previous question be displacing?

9) An object has a volume of 0.5 m3. What is the maximum volume of water it can displace? What weight of water can it displace?

10) The object in the previous problem has a weight of 150 N. Will it float?

11) Is the object in the previous problem more or less dense than water?

#### Outcome 5

11) Calculate the density of the object referred to in the previous problem.

12) An object has a weight of 5.5 N and an apparent weight of 3.5 N when fully submerged. Will the object float?

13) Calculate the density of the object in the previous problem.