a stunt driver's car is moving at 24.2 m/s along a straight road. The road comes to an abrupt stop 21.2 m before a drop off. The coefficient of friction of the road is 0.712, and the coefficient of friction of the dirt between the road and the drop off is 0.426. What is the minimum distance at which the driver can behin to apply the brakes and still prevent himselff from going over the edge?
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1.What is the unit for kinetic energy?
2.A collision in which kinetic energy is conserved is called what?
3. It takes no work to hold a cheerleader in the air, as shown here. If no work is done by the cheerleaders, why do they eventually tire?
| A.The concept of work, as it apples in physics, does not apply to any process that involves people. | |
| B.Their bodies expend chemical energy as their muscles function; this is "hard work," but not the same kind of work that moves a mass over a distance. | |
| C.The arrangement is unstable and they can easily fall over. | |
| D.The cheerleaders at the greater height have more potential energy. | |
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E. Maintaining the same position for a long time is boring. 4.If the orbit is elliptical, rather than circular, what can be said about the work done by the Sun on Earth? a.If the orbit is elliptical, work is done to speed up or to slow down Earth, depending on its location in orbit. b.Whether the orbit is circular or elliptical, work must be done to propel Earth around the Sun. c The work the Sun does on Earth causes the tides. d.The work the Sun does on Earth accounts for Earth's changes of season. E. It does not matter whether the orbit is circular or elliptical, no work is done. 5.In a rollercoaster, provided losses of thermal energy because of friction can be neglected, which of the following is true? A.The kinetic energy decreases as the car moves to the top of the slope. B.The rollercoaster moves at constant speed as its height above the ground increases. C. The gravitational potential energy decreases as the car moves to the top of the slope. D.The mechanical energy decreases as the car moves to the top of the slope. E.The mechanical energy increases as the car moves to the top of the slope. |
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A 18.5 µF spherical capacitor is composed of two metallic spheres, one having a radius twice as large as the other. If the region between the spheres is a vacuum, determine the volume of this region.
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In reaching her destination, a backpacker walks with an average velocity of 1.38 m/s, due west. This average velocity results because she hikes for 6.44 km with an average velocity of 2.52 m/s, due west, turns around, and hikes with an average velocity of 0.405 m/s, due east. How far east did she walk?
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A 50.0 g object is attached to a horizontal spring with a force constant of 5.0 N/m and released from rest with an amplitude of 20.0cm. What is the velocity of the object when it is halfway to the equilibrium position if the surface is frictionless?
(please write out formula used)
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A 25 kg suitcase is being pulled with constant speed by a handle that is at an angle of 26 ∘ above the horizontal. If the normal force exerted on the suitcase is 170 N , what is the force F applied to the handle?
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An air-filled parallel-plate capacitor has a capacitance of 2.0 F when the plate spacing is 1.6 mm. (a) What is the area of the plates? (b) What is the maximum voltage Vmax that can be applied to this capacitor (before dielectric breakdown occurs)? (c) How much charge is stored on the capacitor when Vmax is across it? (d) How much energy is stored on the capacitor when Vmax is across it? (e) A piece of Plexiglas (with a dielectric constant of 2.1) is inserted between the plates, completely filling the space between the plates, while the capacitor remains connected to a battery of emf equal to Vmax. What are the final, new capacitance, charge, and energy?
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Two wooden crates rest on top of one another. The smaller top crate has a mass of m1 = 22 kg and the larger bottom crate has a mass of m2 = 93 kg. There is NO friction between the crate and the floor, but the coefficient of static friction between the two crates is μs = 0.87 and the coefficient of kinetic friction between the two crates is μk = 0.68. A massless rope is attached to the lower crate to pull it horizontally to the right (which should be considered the positive direction for this problem).
1) The rope is pulled with a tension T = 481 N (which is small enough that the top crate will not slide). What is the acceleration of the small crate?
2) In the previous situation, what is the frictional force the lower crate exerts on the upper crate?
3) What is the maximum tension that the lower crate can be pulled at before the upper crate begins to slide?
4) The tension is increased in the rope to 1286 N causing the boxes to accelerate faster and the top box to begin sliding. What is the acceleration of the upper crate?
5) As the upper crate slides, what is the acceleration of the lower crate?
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Just before it landed on the moon, the Apollo 12 lunar lander had a mass of 1.4×104 kg.
Part A
What rocket thrust was necessary to have the lander touch down with zero acceleration?
Express your answer with the appropriate units.
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| Fthrust = |
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Two forces, 80 N and 100 N acting at an angle of 60° with each other, pull on an object. a) What single force would replace the two forces? b) What single force (called the equilibrant) would balance the two forces? Solve graphically (using protractor and ruler) and algebraically (components method).
please anserw in a way i can understand and please do the graph.
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An indy 500 driver is doing 105 m/s, with 100,000 meters and 10s left in a race. Her car can do a maximum acceleration of 15 m/s^2. Can she finish the race? Does she need to accelerate the entire time? If not, what is the minimum amount of time she must accelerate in order to finish the race in 10s?
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The figure below shows a Ferris wheel that rotates five times each minute. It carries each car around a circle of diameter 20.0 m.What force (magnitude and direction) does the seat exert on a 53.0-kg child when the rider is halfway between top and bottom? (direction is measured inward from the vertical)
I got 588.7365. It is telling me i am within 10% of the correct value but i cant seem to get the right answer. i tried again and got 538 which obviously isnt right because the correct answer is within 10% of 588
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A particle with rest energy 8.940 GeV decays at rest into two daughter particles, one with rest energy 6.720 GeV and the other with rest energy 130.000 MeV.
(a) What is the mass of the parent particle?
(b) How much energy is released in the decay?
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1). A car is moving along a straight line defined to be the positive x direction. Its velocity is measured and found to be a function of time given by Vx(t)=(alpha)t^2 , where alpha is a known constant. The car was at the point x = A at the time t = 2sec. Find the car's position as a function of time. How fast would the car be going just before it hits a wall located at x = L? (Give Law or Definition. Give Application. Give Result.) (The professors answer is v(t*)= (alpha)((3(L+8alpha/3-A))/alpha)^2/3) Please give as much explanation as possible!
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why dont we see interference fringes when light shines through a window?
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