s8pe-103cr-ca
12/8/05
6:01 PM
MAZER
Page 94
Thinking Critically
19. APPLY Why is it important for mountain
climbers to know the maximum tension they
can put on a climbing rope? (8.2.e)
20. COMPARE How does the friction between solid
surfaces compare with the friction between a
moving object and a fluid?
21. APPLY Explain why a block of wood gets warm
when it is rubbed with sandpaper.
27. INFER A person weighing 500 N climbs on a
rope. What is the tension on the rope? (8.2.d)
28. COMPARE Trisha
hangs a mass from a
spring as shown in
the picture. The mass
is not moving. Sketch
a diagram showing
the forces acting on
the spring. (8.2.d)
22. PREDICT The Moon’s orbit is gradually
increasing. Each year the Moon is about
3.8 cm farther from Earth than the year
before. How does this change affect the force
of gravity between Earth and the Moon? (8.2.g)
23. APPLY The Moon has one-sixth the gravity
of Earth. Why would it be easier to launch
spacecraft into orbit around the Moon than
around Earth? (8.2.g)
Use the photograph below to answer the next
three questions.
Using Math Skills in Science
Complete the following calculations.
29. How much force does a 10 kg block exert
on the ground? (8.2.d)
30. A 6 kg box is placed on a flat surface. What is
the weight of the box in newtons? What is the
normal force acting on the box? (8.2.d)
24. APPLY A skydiver jumps out of a plane. After
he reaches terminal velocity, he opens his
parachute. Draw a sketch showing the forces
of air resistance and gravity on the skydiver
after the parachute opens. Use a longer arrow
for a greater force. (8.2.e)
25. SYNTHESIZE Why does the skydiver fall down
toward Earth rather than going into orbit? (8.2.g)
26. INFER The Moon has no atmosphere. Would
it be safe to skydive on the Moon? Why or
why not?
94 Unit 1: Motion and Forces
31. ANALYZE Look again at the picture on pages
68–69. What forces are acting on the snowboarder? on the snow?
32. SYNTHESIZE Choose two concepts discussed in
this chapter, and describe how Newton’s laws
relate to those concepts.
Check your schedule for your unit project. How are
you doing? Be sure that you have placed data or
notes from your research into your project folder.
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