Car a starts from a at 5 a.m. and goes to B at the speed of 60 kilometers per hour Car a starts from a at 5:00 in the morning and goes to B at 60 km / h. car B starts from a at 6:30 and goes to B, catching up with car a at 9:30

Car a starts from a at 5 a.m. and goes to B at the speed of 60 kilometers per hour Car a starts from a at 5:00 in the morning and goes to B at 60 km / h. car B starts from a at 6:30 and goes to B, catching up with car a at 9:30

Let B's speed be x km / h
（9.5-6.5)x=(9.5-5)*60
3x=4.5*60
x=4.5*20
x=90
A: B's speed is 90 kilometers per hour

At 5:00 a.m., car a went from place a to place B at the speed of 32 kilometers per hour. At 6:30 a.m., car B started to leave. As a result, at 9:30 a.m,
Car B caught up with car a and asked: what's the speed of car B?
Calculate by equation

The speed of car B is x kilometers per hour
3x=32*4.5
x=48

The speed of train a from a to B is 60 km / h, and that of train B from B to a is 90 km / h. The two trains start from 8:00 a.m. at the same time. It is known that a and B are 200 km apart. What time do they meet?

Let two cars meet after X hours, according to the meaning of the question: 60x + 90x = 200, the solution is: x = 43, a: the two cars meet at 9:20 in the morning

The driver found that the direction of the car's speed changed by 30 ° when the car drove 20 meters in 20 seconds at a constant speed on the horizontal arc curve. The driver estimated that the radius of the curve was______ m. What is the centripetal acceleration of the car______ M / S2. (take 2 significant digits)

(1) According to the meaning of the topic, the arc is the distance in time t, i.e. s = 20m, and the corresponding center angle is 30 degrees. Therefore, according to the geometric relationship, there are: S = 2 π R × 112, so the solution is: r = 38m; (2) from the linear velocity formula v = st = 2020m / S = 1m / s, and then from the centripetal acceleration formula an = V2R = 1238m / S2 = 0.026