The toy car with mass M1 = 1kg moves at a uniform speed of V1 = 0.5m/s on a smooth horizontal plane. A small ball with mass M2 = 0.5kg and velocity v = 0.10m/s flies into the car and moves with the car Find the speed of the car and the ball moving together The impulse of the ball

The toy car with mass M1 = 1kg moves at a uniform speed of V1 = 0.5m/s on a smooth horizontal plane. A small ball with mass M2 = 0.5kg and velocity v = 0.10m/s flies into the car and moves with the car Find the speed of the car and the ball moving together The impulse of the ball

According to the conservation of momentum
m1v1-m2v=(m1+m2)v2
v2=0.3 m/s
The ball is affected by the change of momentum
p=m2(v2+v)=0.02 kgm/s

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In order to reduce the acceleration time and distance on the deck when the fighter takes off, most modern aircraft carriers adopt steam ejection technology. If a fighter with a total mass of 5.0 x 10 ^ 3kg adopts taxiing acceleration (only relying on its own power system acceleration), to achieve the takeoff speed of V0 = 60 / s, the length of the horizontal runway on the deck should be at least 120m, Under the combined action of the fighter's own power and continuous steam power, the take-off speed can be achieved as long as the fighter accelerates horizontally for 60m. Suppose that the fighter moves in a straight line with uniform acceleration during the take-off process, the aircraft carrier remains stationary, and the air resistance remains unchanged, taking g = 10m / S ^ 2. (1) steam ejection technology is adopted, (2) by using steam ejection technology, what is the elastic force of ejection system? What is the work of elastic force on the fighter in the process of accelerating 60?
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(1) If l = VOT / 2 = 60, t = 2S, VO = at, a = 30m / S ^ 2, then f = ma = 1800n (2) l = 120m. Similarly, if a = 15m / S ^ 2, then MVO ^ 2 / 2 = (MA + F ') l, then f' = 7500n, w = f'l = 450000j

Why are there two connection methods of partial voltage and current limiting in resistivity measurement

The voltage dividing method is usually used: the voltage measuring range of the voltage dividing method is large (it can be adjusted from zero), and the distance between multiple measuring points is large

Calculating resistivity by resistance law
Classical electron theory: the motion of electron in metal is like this: under the action of external electric field, the free electron moves directionally, which produces electric current. In the process of motion, the electron constantly collides with metal ions, giving kinetic energy to metal ions, and its kinetic energy is reduced to zero, The average distance between the two collisions is called free path, which is expressed by L. the average velocity of electron motion is shown by V. the number of free electrons per unit volume of conductor is n, the mass of electron is m, and the charge of electron is e, It is proved that the resistivity of metal conductor is 2mV / NE & sup2; L

Please refer to my answer: let the average time interval between two successive collisions of free electrons be: v = a τ acceleration: a = f / M electric field force: F = EE electric field strength: e = u / D average velocity of electrons: V '= V / 2 = a τ / 2 = (F / M) τ / 2 = (EE / M) τ / 2 = (E (U / D) / M) τ / 2 = (EU τ) / (2Md) current