91Ó°ÊÓ

17. Which of the following are inertial reference frames? Explain.

a. A car driving at steady speed on a straight and level road.

b. A car driving at steady speed up a 10° incline.

c. A car speeding up after leaving a stop sign.

d. A car driving at steady speed around a curve.

Exercises 18 show two of the three forces acting on an object in equilibrium. Redraw the diagram, showing all three forces. Label the third force $\stackrel{→}{F_3}$.

Exercise 19 show two of the three forces acting on an object in equilibrium. Redraw the diagram, showing all three forces. Label the third force $\stackrel{→}{F_3}$.

A chandelier hangs from a chain in the middle of a dining

room. Identify the forces on the chandelier.

A compressed spring is pushing a block across a rough horizontal table. How many force vectors would be shown on a free-body diagram? Name them.

Exercises 20 show a free-body diagram. For each, write a short description of a real object for which this would be the correct free-body diagram. Use Examples 5.4, 5.5, and 5.6 as examples of what a description should be like.

Exercises 21 show a free-body diagram. Write a short description of a real object for which this would be the correct free-body diagram. Use Examples 5.4, 5.5, and 5.6 as examples of what a description should be like.

Exercises 22 show a free-body diagram. Write a short description of a real object for which this would be the correct free-body diagram. Use Examples 5.4, 5.5, and 5.6 as examples of what a description should be like.

Exercises 23 describe a situation. For each, identify all forces acting on the object and draw a free-body diagram of the object.

A cat is sitting on a window sill.

Exercises 24 describe a situation. Identify all forces acting on the object and draw a free-body diagram of the object.

An ice hockey puck glides across frictionless ice.