a) Find the dimensions of potential energy. Make sure that you write your answer in the correct dimensional form.[2 marks] b) Determine if the following their usual meanings):are dimensionally correct

or dimensionally incorrect (all letters have \text { (i) } \quad 3 a s+u^{2}=2 v^{2} Figure 3 shows a system of four forces acting at the point O. Determine the resultant of these four forces acting at O in magnitude and direction. Illustrate carefully the directions ofthe component forces, the direction of the resultant force in terms of the angle it makes with the horizontal.[12 marks] \frac{W}{t}=-2.5 P+F v(W=\text { Work done, } P=\text { Power etc. })