2. he five forces shown act at point O. What is the magnitude of the resultant force? (20points) 60 N 50 N 40 N 30 30° 30 30 N 30 20 N

orthogonal to the vector y = (2)? You may want to go through the proof of When is the vector x = projecting y on x and the implications of (intuition behind) "orthogonality".

Can you please help me with this question?

5. Sketch the curve r(t) = (you can plot it in Geogebra first and then transfer on to paper). Can you calculate the vectors T, B and N at t = 0 and at t 2πT? -

9. A vertical tower AO of height h metres stands with its base A on horizontal ground. A stone is projected horizontally from the top O of the tower with speed V ms ¹. The stone moves in a vertical plane under gravity where the acceleration due to gravity is g ms 2. At time t seconds its position vector relative to O is r(t) = Vt i-lgt² j The stone hits the ground at an angle of 45° to the horizontal. What is the time of impact? (A) (B) (C) (D) V 2g V g 2V g 4V g seconds seconds seconds seconds