The stopping distance of a car is the number of feet that the car travels after the driver starts applying the brakes.The stopping distance of a certain car is directly proportional to the square of the speed of the car,in miles per hour,at the time the brakes are first applied.If the car’s stopping distance for an initial speed of 20 miles per hour is 17 feet,what is its stopping distance for an initial speed of 40 miles per hour?
A.34 feet
B.51 feet
C.60 feet
D.68 feet
E.85 feet
As shown in Figure 1,there is a water surface of stopping the boat,the captain L = 3 m,the quality of M = 120 kg,one of the stern from the bow of the ship came,the quality of m = 60 kg.In that case,the distance of boat mobile number?(Water resistance can be ignored)
Process analysis when the stern from the bow of the ship went through the legs and occurred in the role of ship (you can also move around the course that is taken place and the ship collision course intermittent).Ship to study and select the object,as a result of non-water resistance,so the level of system in the direction of conservation of momentum.
May contain a mixture of solid magnesium chloride,calcium carbonate,copper sulfate,potassium carbonate and sodium nitrate in one or several.Experiments are the following:
(1) of the mixture Add enough water,a colorless,transparent solution;
(2) to (1) by adding sodium hydroxide solution is no solution;
(3) in the above (1) of the solution by adding hydrochloric acid,produce air bubbles.
According to the original mixture of the predictable I am sure that many,certainly not,it may be.
Chemical equation that must have occurred in the above-mentioned experimental response.
