8. The cross-bar of a rugby goal post is 3.0 m above the ground. In a training, the ball is kicked from a distance of 22 m from the goal post. The ball leaves the ground at an angle of \( 45^{\circ} \) and just goes over the cross-bar as shown in the figure below. Calculate the initial speed of the ball when it is kicked.

3) One of the following is not a source of magnetostatic fields: A dc current in a wire An electric field linearly changing with time A permanent magnet A charged disk rotating at uniform speed

4) Suppose a uniform electric field exists in the room in which you are working, suc at the lines of force are horizontal and at right angles to one wall. As you walk towar e wall from which the lines of force emerge into the room, are you walking toward Points of lower potential Points of the same potential (equipotential line)? All Choices Are Wrong 5) Which of these statements is not characteristic of a static magnetic field? It is solenoidal. Magnetic flux lines are always closed. It has no sinks or sources All Choices Are Wrong

12 Контур площадью \( 60 \mathrm{~cm}^{2} \) находится в однородном магнитном поле, линии индукции которого перпендикулярны плоскости контура. Чему равен модуль ЭДС индукции, возникающей в этом контуре при равномерном увеличении индукции магнитного поля от 0 Тл до 0,8 Тл за 2 c ?

8. Am Sporttag rennen Melanie und Stefanie gemeinsam den 200-Meter-Laut. Melanie legt 80 m in 14 s zurück und Stefanie braucht für 30 m 6 s . Beide halten ihre Geschwindigkeit während des ganzen Laufes ein. Wie viele Meter vom Ziel entfernt ist Stefanie, wenn Melanie die Ziellinie erreicht?

The resistance, \( R \) newtons, to the motion of a toy car is directly proportional to the square of its speed, \( \mathrm{vm} / \mathrm{s} \). A toy car with speed \( 6 \mathrm{~m} / \mathrm{s} \) experiences a resistance of 9 Newtons. Find the speed of the toy car if it experiences a resistance of 12 Newtons.