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California’s Bay Area Rapid Transit System (BART) uses an automatic braking system triggered by earthquake warnings. The system is designed to prevent disastrous accidents involving trains traveling at a maximum of 112 km/h and carrying a total of some 45,000 passengers at rush hour. If it takes a train 24 s to brake to a stop, how much advance warning of an earthquake is needed to bring a 112-km/h train to a reasonably safe speed of 42 km/h when the earthquake strikes?
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- A train makes a round trip on a straight, level track. The first half of the trip is 300\ \mathrm{km}300 km and is traveled at a speed of 75\ \mathrm{km/ h}75 km/h. After a 0.50\ \mathrm{h}0.50 h layover , the train returns the 300\ \mathrm{km}300 km at a speed of 85\ \mathrm{km/ h}85 km/h. What is the train's (a) average speed and (b) average velocity?arrow_forwardIn the late 1800's, twenty-five percent of the world's nickel production came from Nickel Mines, Pennsylvania. In one mining operation, nickel ore was loaded on carts that rolled on frictionless rails that ran from the dig-site, through the level mine, and were then pulled up a mine shaft inclined at 21.00 above the horizontal by a cable connected to a winch. at the bottom of a 1100 m long ramp and was accelerated at a constant acceleration to a speed of 2.20 m/s in 13.0 s and then continued at this constant speed to the top of the ramp. loaded ore car with a mass of 810 kg started from rest (a) Determine the maximum power the winch motor provides while the cart is accelerating. W (b) Determine the power the winch motor needs to provide when the cart is moving at a constant speed. W (c) What is the total work accomplished by the winch motor by the time a loaded ore cart reaches the end of the ramp? Jarrow_forwardAs a city planner, you receive complaints from local residents about the safety of nearby roads and streets. One complaint concerns a stop sign at the corner of Pine Street and 1st Street. Residents complain that the speed limit in the area (55 mph) is too high to allow vehicles to stop in time. Under normal conditions this is not a problem, but when fog rolls in visibility can reduce to only 155 ft. Since fog is a common occurrence in this region, you decide to investigate. The state highway department states that the effective coefficient of friction between a rolling wheel and asphalt ranges between 0.536 and 0.599, whereas the effective coefficient of friction between a skidding (locked) wheel and asphalt ranges between 0.350 and 0.480. Vehicles of all types travel on the road, from small VW bugs weighing 1410 lb to large trucks weighing 8250 lb. Considering that some drivers will brake properly when slowing down and others will skid to stop, calculate the minimum and maximum…arrow_forward
- As a city planner, you receive complaints from local residents about the safety of nearby roads and streets. One complaint concerns a stop sign at the corner of Pine Street and 1st Street. Residents complain that the speed limit in the area (55 mph) is too high to allow vehicles to stop in time. Under normal conditions this is not a problem, but when fog rolls in visibility can reduce to only 155 ft. Since fog is a common occurrence in this region, you decide to investigate. The state highway department states that the effective coefficient of friction between a rolling wheel and asphalt ranges between 0.689 and 0.770, whereas the effective coefficient of friction between a skidding (locked) wheel and asphalt ranges between 0.450 and 0.617. Vehicles of all types travel on the road, from small VW bugs weighing 1210 lb to large trucks weighing 8640 lb. Considering that some drivers will brake properly when slowing down and others will skid to stop, calculate the minimum and maximum…arrow_forwardAs a city planner, you receive complaints from local residents about the safety of nearby roads and streets. One complaint concerns a stop sign at the corner of Pine Street and 1st Street. Residents complain that the speed limit in the area (55 mph) is too high to allow vehicles to stop in time. Under normal conditions this is not a problem, but when fog rolls in visibility can reduce to only 155 ft. Since fog is a common occurrence in this region, you decide to investigate. The state highway department states that the effective coefficient of friction between a rolling wheel and asphalt ranges between 0.536 and 0.599, whereas the effective coefficient of friction between a skidding (locked) wheel and asphalt ranges between 0.350 and 0.480. Vehicles of all types travel on the road, from small VW bugs weighing 1310 lb to large trucks weighing 8.40 x 10° lb. Considering that some drivers will brake properly when slowing down and others will skid to stop, calculate the minimum and maximum…arrow_forwardWhen visiting a friend in Atlanta you decide to drive around the city. You turn a corner and are driving up a steep hill. Suddenly, a small boy runs out on the street chasing a ball. You slam on the brakes and skid to a stop leaving a 50-foot-long skid mark on the street. The boy calmly walks away but a policemen watching from the sidewalk walks over and gives you a speeding ticket. He points out that the speed limit on this street is 25mph. After you recover your wits, you begin to examine the situation. You determine that the street makes an angle of 25◦ with the horizontal and that the coefficient of static friction between your tires and the street is 0.80. You also find that the coefficient of kinetic friction between your tires and the street is 0.60. Your car’s information book tells you that the mass of your car is 1600 kg. You weigh 140 lbs. Will you fight the ticket in court? Please draw a figure with your detailed answer.arrow_forward
- When visiting a friend in Atlanta you decide to drive around the city. You turn a corner and are driving up a steep hill. Suddenly, a small boy runs out on the street chasing a ball. You slam on the brakes and skid to a stop leaving a 50-foot-long skid mark on the street. The boy calmly walks away but a policemen watching from the sidewalk walks over and gives you a speeding ticket. He points out that the speed limit on this street is 25mph. After you recover your wits, you begin to examine the situation. You determine that the street makes an angle of 25◦ with the horizontal and that the coefficient of static friction between your tires and the street is 0.80. You also find that the coefficient of kinetic friction between your tires and the street is 0.60. Your car’s information book tells you that the mass of your car is 1600 kg. You weigh 140 lbs. Draw a figure for this question. Will you fight the ticket in court?arrow_forwardA car starts moving at 60 mi/hr. After some time, the car speed reduces to 40 mi/hr and stays there for the rest of the trip. The entire trip takes 5 hours and covers 280 miles. For what distance did the car move at 60 mi/hr? Question 8 options: 40 mi 200 mi 240 miarrow_forwardA man decided to ride his car at 10 kph for the first 5 seconds. He then accelerates at 1 m/s for the next 5 seconds, 2 m/s for the next 5 seconds, 3 m/s2 for the next 5 seconds, and so on and so forth. (a) At what time will he reach a velocity of 60 kph? (b) What is the total distance (m) traveled after he has reached a velocity of 60 kph?arrow_forward
- Amel goes for a walk with a speed of 3kph. After 30 minutes of walk, his wife follows him. Walking 3.25 km for the first hour, 3.75 km for the second hour, 4 km for the third hour and so on maintaining a speed of .25 km per hour. How many hours does the wife take to catch up to her husband?arrow_forwardA graph of v(t) is shown for a world-class track sprinter in a 100-m race. (See figure below). Runner Velocity vs. Time Velocity (m/s) 14 12 2086 2 0 2 6 Time (s) 8 10 12 (a) What is his average velocity (in m/s) for the first 4 s? m/s (b) What is his instantaneous velocity (in m/s) at t = 6 s? m/s (c) What is his average acceleration (in m/s²) between 0 and 4 s? m/s² (d) What is his time (in s) for the race? Sarrow_forwardYou are a police officer examining the scene of a car crash that claimed the life of someone driving a Tesla. There was a collision involving them and a pickup truck. The truck driver, who survived, said he was travelling North into the intersection and the Tesla was travelling East into the intersection. The truck driver claims that he was not exceeding the speed limit when the accident occurred. You note the posted speed limit was 80 km/h. Like airplanes, Teslas have a black box that records various statistics in the event a collision occurs. After analyzing the data from the black box, you discover the Tesla was driving at a velocity of 69.6 km/h [E] when the collision occurred. You google the mass of both of the vehicles and find the Tesla should be about 2020 kg and the truck should be about 2820 kg. During the collision, the two vehicles crumpled and became entangled, the skid marks revealing that the two vehicles travelled E 68° N after impact. How fast, in km/h, was the truck…arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
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