High 2 simple physics problems will be done

1.Untie. The electric field force experienced by Q is directed towards the center of the sphere, indicating that the ball A is positively charged.

Brought in data (without direction).

q=10e(-8)*

That is, the charge of the ball is to the minus 9th power of q = 1x10.

e=k*(q r 2), which is obtained by substituting the data.

The field strength of point A is e=c m, and the direction is divergence from ball A, that is, from ball A to the direction of point charge q.

The point charge field strength has nothing to do with the presence or absence of the tentative charge, and the field strength remains unchanged.

2.Untie. According to the title, f mg=tan30=eq to obtain e=10e7

i.e. 1x10 to the 7th power v m

The direction is the direction in which the dangling line deviates from the vertical direction.

If q is removed, the electric field magnitude is still ea=100V m2, and the tensile force, gravity, and electric field force of the rope form a vector triangle, which has a geometric relationship.

EQ (mg) = Tan30 E = 10 7V m direction in the direction of the rope offset (if the ball is positively charged).

If the ball is negatively charged, it points in the opposite direction.

Categories: Education Science >> Admission >> College Entrance Examination Problem Description:

1.The fire leakage car accelerates evenly along the straight rails, and the speed when passing a certain road sign is, and after 1 minute, it becomes 54km h, and the acceleration of the train is obtained.

Parse: v0=

v=54km /h=15m/s

t=1mint=60s

The acceleration of the fire Li search car.

a=(v-v。t=(15-3) 60=meter quadratic seconds.

Good luck with your learning and progress.

1.The mechanical energy of the wood block is conserved during the ascent process: (1 2) MV2 2=MGH, and V2=4M s is obtained

The dynamic attitude of the system is conserved at the moment of collision: mv0=mv1+mv2, and v1=480m s

Brief book trillion f + mg = ma, get a = 5g = 20m s 2 bullets on the whole process of blocking rent and liter: v1 = at, get t =

1 Two methods (1), take two balls and rods as a system, and later obtain that the height of the center of gravity of the system is h+(lsin@)2, then the total potential energy of the system is 2mg*[h+(lsin@)2], the kinetic energy from rest is 0, and the mechanical energy is conserved, so the velocity when moving on a smooth plane is v

From the equilibrium condition: f electricity = mgtan

Again f electricity = qe

Solution, the electric field strength at the place where the ball is located: E=mgtan Q The ball has a positive charge, and the direction of the electric field strength is consistent with the direction of the electric field force it receives, and the direction is horizontal to the right, so the electric field strength at the place where the ball is located is mgtan q, and the direction is horizontal to the right.

Question 1: Let the starting acceleration be a, the time is t, and the later acceleration is a, and the time t is obtained by the question: at=v

at=v has: at=at

where t=4s, t=8s, substituting a=2a, so a a=1 2 second question: the first question: v=s t substituting the data to get v=40 kilometers per hour, the second question: average velocity v = total displacement s total time t

Total displacement s = 60 km (as determined by the title).

Total time t = time before 1 3 + time after 2 3 = 20 40 + average speed v = 20 km/h.

Looking at the figure, the conservation of momentum and energy is used twice, and the four formulas are columned, and the simultaneous solution v is obtained

Horizontal momentum is conserved, and it can be solved!

Solution: Because the resultant force of the tensile force f and the gravitational force g must be downward in the direction of the straight rod, and the force of the axis o on the straight rod forms a closed mechanical triangle, so there is: f g = tan30

So g=10