Get college assignment help at uniessay writers A laser beam of wavelength 400 nm is directed at the moon through a 72 in telescope (i.e., the effective diameter of the aperture is 72 in). Estimate the area of the beam by the time it reaches the moon. Answer in units of m2.
How fast (in rpm) must a centrifuge rotate if a particle 6.00 cm from the axis of rotation is to experience an acceleration of 95,000 g’s? rpm A 1500 kg car rounds a curve of radius 70 m banked at an angle of 12°. If the car is traveling at 80 km/h, will a friction force be required? Yes No If so, how much force? (Enter zero if there is no friction force.) N In what direction? down the slope up the slope force is zero You are explaining why astronauts feel weightless while orbiting in the space shuttle. Your friends respond that they thought gravity was just a lot weaker up there. Convince them and yourself that it isn’t so by calculating the acceleration of gravity 276 km above the Earth’s surface in terms of g. (The mass of the Earth is 5.97 1024kg, and the radius of the Earth is 6380 km.) g’ = g Suppose that a binary star system consists of two stars of equal mass. They are observed to be separated by 360 million kilometers and take 5.0 Earth years to orbit about a point midway between them. What is the mass of each? kg A jet pilot takes his aircraft in a vertical loop (Fig. 5-43). Figure 5-43. (a) If the jet is moving at a speed of 2000 km/h at the lowest point of the loop, determine the minimum radius of the circle so that the centripetal acceleration at the lowest point does not exceed 6.0 g’s. m (b) Calculate also the 70 kg pilot’s effective weight (the force with which the seat pushes up on him) at the bottom of the circle. N (c) Calculate the pilot’s effective weight at the top of the circle. (Assume the same speed.) N A curve of radius 55 m is banked for a design speed of 80 km/h. If the coefficient of static friction is 0.30 (wet pavement), at what range of speeds can a car safely make the curve? minimum km/h maximum km/h You are an astronaut in the space shuttle pursuing a satellite in need of repair. You are in a circular orbit of the same radius as the satellite (430 km above the Earth), but23 km behind it. (a) How long will it take to overtake the satellite if you reduce your orbital radius by 1.0 km? hr (b) By how much must you reduce your orbital radius to catch up in 7.0 hours? m Amtrak’s high speed train, the Acela, utilizes tilt of the cars when negotiating curves. The angle of tilt is adjusted so that the main force exerted on the passengers, to provide the centripetal acceleration, is the normal force. The passengers experience less friction force against the seat, thus feeling more comfortable. Consider an Acela train that rounds a curve with a radius of 680 m at a speed of 160 km/h (approximately 100 mi/h). (a) Calculate the friction force needed on a train passenger of mass 75 kg if the track is not banked and the train does not tilt. N (b) Calculate the friction force on the passenger if the train tilts to its maximum tilt of 8° toward the center of the curve. N
Comic-book superheroes are sometimes able to punch holes through steel walls. (a) If the ultimate shear strength of steel is taken to be 2.40 109 Pa, what force is required to punch through a steel plate 1.90 cm thick? Assume the superhero’s fist has cross-sectional area of 1.00 102 cm2 and is approximately circular. (b) Qualitatively, what would happen to the superhero on delivery of the punch? What physical law applies?
A solar sail is made of aluminized Mylar having an emissivity of 0.03 and reflecting 97% of the light that falls on it. Suppose a sail with area 1.20 km2 is oriented so that sunlight falls perpendicular to its surface with an intensity of 1.40 103 W/m2. To what temperature will it warm before it emits as much energy (from both sides) by radiation as it absorbs on the sunny side? Assume the sail is so thin that the temperature is uniform and no energy is emitted from the edges. Take the environment to be 0 K. (σ = 5.6696 10-8 W/m2·K4) Answer in K
In static equilibrium a spring is stretched 0.25 m by a hanging mass. If the system is initially moved up to the unstretched position and released with zero velocity, determine position of the mass (in m) after 4.2s. Take the equilibrium position to be zero and up the positive direction.
An 9.80 kg ball, hanging from the ceiling by a light wire 135 cm long, is struck in an elastic collision by a 1.80 kg ball moving horizontally at 3.50 m/s just before the collision
Some clear food wraps can be highly stretched over a container
A child is twirling a 0.012 kg ball on a string in a horizontal circle whose radius is .100 meters. The ball travels once around the circle in .500 seconds.. A) Determine the centripetal force acting on the ball B) By what factor does the centripetal force increase if the speed of the ball is doubled?
°The press box at a baseball park is 40.0ft above the ground. A reporter in the press box looks at an angle of 20.0° below the horizontal to see second base.
A 150-N child is in a swing that is attached to ropes 2.20 m long. Find the gravitational potential energy associated with the child relative to her lowest position at the following times.
Get college assignment help at uniessay writers A gun shoots bullets that leave the muzzle with a speed of 341 . If a bullet is to hit a target 177 away at the level of the muzzle, the gun must be aimed at a point above the target. How far above the target is this point? (Neglect air resistance.)
A rocket is launched at an angle of 53 degrees above the horizontal with an initial speed of 100 m/s. It moves for3s along its initial line of motion with an overall acceleration of 30 m/s^2. At this time its engine fails and the rocket proceeds to move as a free body. A. What is the rocket’s maximum altitude (height)? B. What is the rocket’s total time of flight? C. What is the rocket’s horizontal range?
Water flows over a dam at the rate of 550 kg/s and falls vertically 80 m before striking the turbine blades. Calculate: (a) the speed of the water just before striking the turbine blades (neglect air resistance), and (b) the rate at which mechanical energy is transferred to the turbine blades, assuming 60 percent efficiency.
a 3kg block is observedto accelerate at a rate twice that of a 6kg block. is the net force acting on the 3kg block therefore twice as large as that acting on the 6kg block
An airplane flies due south at 190 km/h relative to the air. There is a wind blowing at 73 km/h to the east relative to the ground. What are the plane’s speed and direction relative to the ground?
A string under a tension of 47.0 N is used to whirl a rock in a horizontal circle of radius 2.60 m at a speed of 21.0 m/s. The string is pulled in and the speed of the rock increases. When the string is 1.00 m long and the speed of the rock is 51.0 m/s, the string breaks. What is the breaking strength (in newtons) of the string?
an 18 gram rifle bullet traveling 230m/s buries itself in a 3.6 kg pendulum hanging on a 2.8-m-long string, which makes the pendulum swing upward in an arc. Determine the horizontal component of the pendulum’s displacement
A river flows due east at 1.52 m/s. A boat crosses the river from the south shore to the north shore by maintaining a constant veloc- ity of 10.9 m/s due north relative to the water. a) What is the magnitude of the velocity of the boat as viewed by an observer on shore?
Can you please help with these two questions. Thanks
A neutron star has a mass of (about the mass of our sun) and a radius of (about the height of a goodsized mountain). Suppose an object falls from rest near the surface of such a star. How fast would it be moving after it had fallen a distance of 0.010 m? (Assume that the gravitational force is constant over the distance of the fall, and that the star is not rotating.)
14) Glowing plasma is evident in the light from A) a fluorescent lamp. B) the aurora borealis (northern lights). C) an incandescent lamp. D) both a and b. E) both a and c.
The post A laser beam of wavelength 400 nm is directed at the appeared first on uniessay writers.