12 In this question the unit vectors \(\mathbf { i }\) and \(\mathbf { j }\) are horizontal and vertically upwards respectively.
A particle has mass 2 kg .
- Write down its weight as a vector.
A horizontal force of 3 N in the \(\mathbf { i }\) direction and a force \(\mathbf { F } = ( - 4 \mathbf { i } + 12 \mathbf { j } ) \mathrm { N }\) act on the particle.
- Determine the acceleration of the particle.
- The initial velocity of the particle is \(5 \mathbf { i } \mathrm {~ms} ^ { - 1 }\).
Find the velocity of the particle after 4 s .
- Find the extra force that must be applied to the particle for it to move at constant velocity.