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Physics calculation, formula, formula, 1. On October 31, 2009, Chongming Bridge on the Yangtze River was officially opened to traffic. The total length of the bridge is about 25000m. A car with a weight of 2.0 times 10 and three times a kilogram takes 1250 seconds from the east to the west of the bridge, and the resistance is 2.0 times 10 and three times a kilogram, Question (1) what is the speed of the car from the east to the west of the bridge? (2) what is the work of the car's gravity? (3) what is the power of the car at this time? 2. The mass of object a is 50 kg. If the rope is pulled by a force F of 100 N, the object will move at a constant speed of 0.1 M / S. (excluding the weight of rope and pulley) (this pulley is a moving pulley) find: (1) the friction force on object a; (2) the length of the rope pulled in 2 minutes (assuming that the rope is long enough) (3) the work done by force F; (4) the power done by force F
1.(1)25000m÷1250s=20m/s(2)W=Fs=2×10³N×25000=5×10^7J
(3)w'=F's=2×10^4N×25000m=5×10^8J p=W/t=5x10^8j/1250s=4×10^5W
2. No picture
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