Calcular la proyección del vector \( \vec{u}=(-3,2,1) \) sobre el vector \( \vec{v}=(-1,2,4) \) a. \( \vec{w}=\left(-\frac{11}{21}, \frac{22}{21},-\frac{44}{21}\right) \) b. \( \vec{w}=\left(-\frac{11}{21}, \frac{22}{21}, \frac{44}{21}\right) \) c. \( \vec{w}=\left(-\frac{11}{21},-\frac{22}{21}, \frac{44}{21}\right) \) d. \( \vec{w}=\left(\frac{11}{21}, \frac{22}{21},-\frac{44}{21}\right) \)

7. माध्यावस्था पर सरल आवर्ती दोलनक की स्थितिज ऊर्जा 20 J है ओ चरम स्थिति पर 100 J है । तो माध्य स्थिति पर गतिज ऊर्जा है- \( \begin{array}{llll}\text { (1) } 120 \mathrm{~J} & \text { (2) } 100 \mathrm{~J} & \text { (3) } 80 \mathrm{~J} & \text { (4) } 20 \mathrm{~J}\end{array} \)

2) By saying that the electrostatic field is conservative, we do not mean that All Choices Are Wrong The potential difference between any two points is zero. lts circulation is identically zero. Its curl is identically zero. It is the gradient of a scalar potential.

एक सरल आवर्ती दोलक की गतिज ऊर्जा 10 Hz की आवृत्ति दोलित होती है । दोलक एक चरम स्थिति से दूसरी स्थिति तक कि समय लेगा? \( \begin{array}{llll}\text { (1) } 0.1 \mathrm{~s} & \text { (2) } 0.2 \mathrm{~s} & \text { (3) } 0.4 \mathrm{~s} & \text { (4) } 0.5 \mathrm{~s}\end{array} \)

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

2 Se un oggetto giunge a terra con velocità \( v \) caden- do da fermo dall'altezza \( h \), con quale velocità vi giunge cadendo dall'altezza \( 9 h \) ? \( \begin{array}{ll}\text { (a) } v & \text { d } 9 v \\ \text { b } 81 v & \text { (e) } 1,5 v \\ \text { c } 3 v & \end{array} \)