Mass M 8 kg trolley 10

Before placing a small block, a=f, m=1m, s2

When reached. Put on the object of m=2kg.

Friction force f=2*

So the block acceleration a1= f m= velocity is 0, and the trolley acceleration a2=(f-f) m= velocity is.

When time t has elapsed and two objects have the same velocity, let the velocity be v, then there is the equation.

v=a1 * t (I don't bother to solve the equation).

v= * t

Solve the equation to get the value of v and the value of t.

a) If t seconds.

Then the answer displacement s=squared) meters.

b) If t < seconds.

then s1=squared) meters.

After that, the two 0 objects move together Acceleration a3= f (m+m) = so s2= a2 * squared] meter.

Total displacement s = s1 + s2

There are some calculations to solve the equations, I don't bother to do it, you should be able to.

In addition, I almost forgot the things in high school......Maybe it's not the easiest way to do it, but I think it's right.

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When the car passes through the curve, the gravity and elastic force fully provide the centripetal force, indicating that the car has no relative movement trend with the road surface, and the friction force is 0, then n*sin45=mv

After substituting the value, v=10m s,

Answer: <>

Solution: According to Newton's second law, there is: n-mg=mv

r then n mg + mv

rn=10n+

n n According to Newton's third law, the pressure of the exciton on the bridge deck is equal to the n front. Answer: The pressure on the surface of the bridge is n

Solution: After the person jumps out, when the speed of the two cars is exactly the same, it not only avoids collision, but also the speed of the person is the smallest, which is obtained by the law of conservation of momentum.

m+m)v0=mv+mv people.

mv human - mv0 = (m+m)v

The above two formulas are combined.

Solution, v person =

Take the horizontal to the right as the positive direction, take car A, car B and man-made system, and get it from the law of conservation of momentum

m+m)v0-mv0=(m+m)vb+mva (4 points) to substitute the data, and the solution is: va= (2 points).

So, the speed of car A is magnitude and the direction is to the left (2 minutes).