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At a certain point along the path in projectile motion, the projectile has a velocity whose scalar components are *v*_{x} = +30 m/s and *v*_{y} = +40 m/s. As the projectile moves along the path, what would be its *minimum* speed?

= 50 m/s

(30 m/s)^{2} + (40 m/s)^{2} |

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km/s

A bird watcher meanders through the woods, walking 0.25 km due east, 0.75 km due south, and 2.35 km in a direction 42.0° north of west. The time required for this trip is 2.50 h.

(a) Determine the magnitude and direction (relative to due west) of the bird watcher's displacement. Use kilometers and hours for distance and time, respectively.

(b) Determine the magnitude and direction (relative to due west) of the bird watcher's average velocity.

magnitude | km |

direction | ° north of west |

(b) Determine the magnitude and direction (relative to due west) of the bird watcher's average velocity.

magnitude | km/hr |

direction | ° north of west |

v = |

m

m/s

m

(a) How much time passes before the fish's speed doubles?

s

(b) How much additional time would be required for the fish's speed to double again?

s

s

(b) How much additional time would be required for the fish's speed to double again?

s

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A man is standing on a platform that is connected to a pulley arrangement, as the drawing shows. By pulling upward on the rope with a force the man can raise the platform and himself. The total mass of the man plus the platform is 85.5 kg. What pulling force should the man apply to create an upward acceleration of 1.18 m/s^{2}?

N

N

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The drawings show identical blocks at rest on three different inclines, each block held in place by static friction. Rank the forces of static friction in the three cases in ascending order (smallest first).

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An object is moving at a constant velocity. All but one of the following statements could be true. Which one cannot be true?

Question Part |

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An airplane has a mass of 30,500 kg and takes off under the influence of a constant net force of 39,000 N. What is the net force that acts on the plane's 70 kg pilot?

N

N

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The space probe *Deep Space I* was launched on October 24, 1998. It's mass was 474 kg. The goal of the mission was to test a new kind of engine called an ion propulsion drive. This engine generated only a weak thrust, but it could do so over long periods of time with the consumption of only small amounts of fuel. The mission was spectacularly successful. At a thrust of 51 mN how many days were required for the probe to attain a velocity of 905 m/s (2025 mi/h), assuming that the probe started from rest and that the mass remained nearly constant?

days

days

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Two forces *F*_{A} and *F*_{B} are applied to an object whose mass is 17.0 kg. The larger force is *F*_{A}. When both forces point due east, the object's acceleration has a magnitude of 1.20 m/s^{2}. However, when *F*_{A} points due east and *F*_{B} points due west, the acceleration is 0.600 m/s^{2}, due east. Find the magnitude of *F*_{A} and the magnitude of *F*_{B}.

F_{A} = N |

F_{B} = N |

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A space probe has two engines. Each generates the same amount of force when fired, and the directions of these forces can be independently adjusted. When the engines are fired simultaneously and each applies its force in the same direction, the probe, starting from rest, takes 19 s to travel a certain distance. How long does it take to travel the same distance, again starting from rest, if the engines are fired simultaneously and the forces that they apply to the probe are perpendicular?

s

s

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A raindrop has a mass of 8.9 10^{-7} kg and is falling near the surface of the earth. Calculate the magnitude of the gravitational force exerted in the following.

(a) on the raindrop by the earth

(b) on the earth by the raindrop

GO Tutorial
F_{raindrop} |
= |

(b) on the earth by the raindrop

F_{earth} |
= |

m/s

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The drawing (not to scale) shows one alignment of the sun, earth, and moon. The gravitational force _{SM} that the sun exerts on the moon is perpendicular to the force _{EM} that the earth exerts on the moon. The masses are: mass of sun = 1.99 10^{30} kg, mass of earth = 5.98 10^{24} kg, mass of moon = 7.35 10^{22} kg. The distances shown in the drawing are *r*_{SM} = 1.5 10^{11} m and*r*_{EM} = 3.85 10^{8} m. Determine the magnitude of the net gravitational force on the moon.

N

N

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A rocket blasts off from rest and attains a speed of 44 m/s in 14 s. An astronaut has a mass of 58.3 kg. What is the astronaut's apparent weight during take off?

N

N

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A car is traveling up a hill that is inclined at an angle θ above the horizontal. Determine the ratio of the magnitude of the normal force to the weight of the car when θ is equal to the following.

(a) θ = 15°

Ratio =

(b) θ = 37°

Ratio =

GO Tutorial
Ratio =

(b) θ = 37°

Ratio =

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Three forces act on a moving object. One force has a magnitude of 81.5 N and is directed due north. Another has a magnitude of 58.0 N and is directed due west. What must be the magnitude and direction of the third force, such that the object continues to move with a constant velocity?

magnitude | N |

direction | ° south of east |

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The drawing shows a wire tooth brace used by orthodontists. The topmost tooth is protruding slightly, and the tension in the wire exerts two forces and ' on this tooth in order to bring it back into alignment. If the forces have the same magnitude of 25.0 N, what is the magnitude of the net force exerted on the tooth by these forces?

N

N

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<cj7link(cj7_p4-5.pdf)>A 14.5-g bullet is fired from a rifle. It takes 2.15 10^{-3} s for the bullet to travel the length of the barrel, and it exits the barrel with a speed of 640 m/s. Assuming that the acceleration of the bullet is constant, find the average net force exerted on the bullet.

N

N

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A rescue helicopter is lifting a man

(weight = 849 N)

from a capsized boat by means of a cable and harness.
(a) What is the tension in the cable when the man is given an initial upward acceleration of 1.17 m/s^{2}?

N

(b) What is the tension during the remainder of the rescue when he is pulled upward at a constant velocity?

N

N

(b) What is the tension during the remainder of the rescue when he is pulled upward at a constant velocity?

N

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Interactive Solution 4.11 offers help in modeling this problem.

Two forces,_{1} and _{2}, act on the 5.00 kg block shown in the drawing. The magnitudes of the forces are *F*_{1} = 32.0 N and *F*_{2} = 40.5 N. What is the horizontal acceleration (magnitude and direction) of the block?

m/s^{2}

Two forces,

m/s

Subject | Science |

Due By (Pacific Time) | 11/02/2014 12:00 am |

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