1.2.5m/s omitted; 10m/s； 0; Uniformly accelerated straight line with non-zero initial velocity; 0.5m/S2； 75m uniform straight line; 300m uniform deceleration straight line; - 1m/S2； 50m 3.8m/S2； 80m 4.607m/s； 7520m 5.2m/S2； 5s 6。 -2.4m/S2 7. 196.6m； 5.62s 8. 12m/s； -0.6 m/s 2

Group b

9. Ball A moves in a straight line at a uniform speed, with speed v =-0.2m/s; Ball B moves in a straight line with uniform acceleration, with zero initial velocity and acceleration a =-3.2m/S2; Ball C moves in a straight line at a uniform speed, with initial velocity v0 = 0.34m/s and acceleration a =-0.8m/S2; The ball D moves in a straight line with uniform acceleration, the initial velocity is zero, and the acceleration is a = 4m/S2. For variable-speed motion, the basic method to solve this problem is to take any two sets of displacement and time data for each ball: (s 1, t 1) and (s2, t2), substitute them into the displacement formula to solve the initial velocity and acceleration, and then take the third set of data for verification. No, but at this time, the two cars are only 65438+. 165m 13。 (1) A = 3m/S2, and the direction points uphill (2) slightly 14. No, 12.58m/s2.