Figure 2-45 shows a simple device for measuring your reaction time. It consists of a cardboard strip marked with a scale and two large dots. A friend holds the strip vertically, with thumb and forefinger at the dot on the right in Fig. 2-45. You then position your thumb and forefinger at the other dot (on the left in Fig. 2-45), being careful not to touch the strip. Your friend releases the strip, and you try to pinch it as soon as possible after you see it begin to fall. The mark at the place where you pinch the strip gives your reaction time. (a) How far from the lower dot should you place the 50.0 ms mark? How much higher should you place the marks for (b) 100, (c) 150, (d) 200, and (e) 250 ms? (For example, should the 100 ms marker be 2 times as far from the dot as the 50 ms marker? If so, give an answer of 2 times. Can you find any pattern in the answers?)
Figure 2-45 shows a simple device for measuring your reaction time. It consists of a cardboard strip marked with a scale and two large dots. A friend holds the strip vertically, with thumb and forefinger at the dot on the right in Fig. 2-45. You then position your thumb and forefinger at the other dot (on the left in Fig. 2-45), being careful not to touch the strip. Your friend releases the strip, and you try to pinch it as soon as possible after you see it begin to fall. The mark at the place where you pinch the strip gives your reaction time. (a) How far from the lower dot should you place the 50.0 ms mark? How much higher should you place the marks for (b) 100, (c) 150, (d) 200, and (e) 250 ms? (For example, should the 100 ms marker be 2 times as far from the dot as the 50 ms marker? If so, give an answer of 2 times. Can you find any pattern in the answers?)
Figure 2-45 shows a simple device for measuring your reaction time. It consists of a cardboard strip marked with a scale and two large dots. A friend holds the strip vertically, with thumb and forefinger at the dot on the right in Fig. 2-45. You then position your thumb and forefinger at the other dot (on the left in Fig. 2-45), being careful not to touch the strip. Your friend releases the strip, and you try to pinch it as soon as possible after you see it begin to fall. The mark at the place where you pinch the strip gives your reaction time. (a) How far from the lower dot should you place the 50.0 ms mark? How much higher should you place the marks for (b) 100, (c) 150, (d) 200, and (e) 250 ms? (For example, should the 100 ms marker be 2 times as far from the dot as the 50 ms marker? If so, give an answer of 2 times. Can you find any pattern in the answers?)
What is the sum of the following four vectors in (a) unit-vector notation, and as (b) a magnitude and (c) an angle? Positive angles are counterclockwise from the positive direction of the x axis; negative angles are clockwise.
A→=(2.00m)î+(3.00m)ĵB→ = 4.00 m, at 65.0°C→=(-4.00m)î-(6.00m)ĵD→ = 5.00 m, at -235°
2-42. A solid cube of uniform density and sides of b is in equilibrium on top of a cylinder
of radius R (Figure 2-C). The planes of four sides of the cube are parallel to the axis
of the cylinder. The contact between cube and sphere is perfectly rough. Under
what conditions is the equilibrium stable or not stable?
R
FIGURE 2-C Problem 2-42.
35. ssm Vector A points along the +y axis and has a magnitude of 100.0
units. Vector B points at an angle of
60.0° above the +x axis and has a
magnitude of 200.0 units. Vector Č
points along the +x axis and has a
magnitude of 150.0 units. Which vec-
tor has (a) the largest x component and
(b) the largest y component?
E
30.0
Ā,
36. Soccer player #1 is 8.6 m from
the goal (see the drawing). If she
kicks the ball directly into the net, the
ball has a displacement labeled A.
Net
If, on the other hand, she first kicks it
90°
to player #2, who then kicks it into the
net, the ball undergoes two successive
displacements, A, and A,. What are
the magnitudes and directions of Ā,
and A,?
Problem 36
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University Physics with Modern Physics (14th Edition)
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