A tennis ball of mass 0.2 kg is moving with velocity \(( - 10 \mathbf { i } ) \mathrm { m } \mathrm { s } ^ { - 1 }\) when it is struck by a tennis racket. Immediately after being struck, the ball has velocity \(( 15 \mathbf { i } + 15 \mathbf { j } ) \mathrm { m } \mathrm { s } ^ { - 1 }\). Find
- the magnitude of the impulse exerted by the racket on the ball,
- the angle, to the nearest degree, between the vector \(\mathbf { i }\) and the impulse exerted by the racket,
- the kinetic energy gained by the ball as a result of being struck.
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A uniform lamina \(A B C D\) is made by taking a uniform sheet of metal in the form of a rectangle \(A B E D\), with \(A B = 3 a\) and \(A D = 2 a\), and removing the triangle \(B C E\), where \(C\) lies on \(D E\) and \(C E = a\), as shown in Fig. 1.