(20 1 1? As shown in the figure, put the car with mass M=8kg on a level and smooth plane, and add a horizontal thrust F=8N at the left end of the car.

(1) Taking small objects as the research object, it is obtained by Newton's second law:

μmg=ma 1

Solution: a 1=μg=2m/s2.

Taking the automobile as the research object, from Newton's second law:

F-μmg=Ma2

Solution: A2 = f? μmgM=0.5m/s2

Therefore, the acceleration of a small object is a 1=2m/s2, and that of a car is A2 = 0.5m/S2.

(2) The kinematic formula is a 1t=v0+a2t.

Solution: t = v0a 1? a2= 1s

Then: x1=12a1T2 =1m.

x2 = v0t+ 12a2t 2 = 1.75m

L = x2-x1= 0.75m.

Therefore, the length of the car is 0.75 m.