### Northwest mock advance level June 2020 math mechanics 3

Northwest mock advance level June 2020 math mechanics 3

The positon vector r of a particle of mass 2 kg at time / seconds is given by

r = [(2 sin 2t ) i + (1 – cos 2t ) j] m.

Find

(a) the velocity and the acceleration of the particle when / =-,

(b) the kinetic ernegy of the particle when / =

(c) the force acting on the particle when / =-,

(d ) the values of t where 0 < t – for which the velocity of the particle is perpendicular

to its acceleration.

2. (a) acts A force at the Fi,point of magnitude ( 1, 4). Given 12^5that N,Fi acts and at Fthe 2 form pointa(couple I, 7) towards . Find the thecartesian point (7,equation 10). Another of theforce line,ol F2action

of F:and the magnitude of the couple. (8 marks)

(b) An clastic string AB of natural length 2 m has the end A fixed. A load of mass 4 kg is attached to the

other end B so that the system hangs freely in equilibrium. Find the work that must be done to extend the

unloaded string from a length of 2.5 m to 2.9 m. (5 marks

## Ngeh

April 19, 2022

Really nice