Question 1 :- A boat is rowed at a velocity of 20 km/hour across a river. The velocity of stream is 8 km/hour. Determine the resultant velocity of the boat.
Solution:
Taking downstream direction as x and direction across the river as y, it is given that
Vx = 8 km/hour Vy = 20 km/hour
The resultant velocity
V=√(8²+20²) =21.54 km/hour
α = tan-¹ Vy/Vx= tan-¹ 20/8
=68.20°
Question 2:- The guy wire of the electrical pole shown in Fig. 1.9(a) makes 60° to the horizontal and is carrying a force of 60 kN. Find the horizontal and vertical components of the force.
Solution:
Figure (b) shows the resolution of force
F = 20 kN
into its components in horizontal and vertical components.
From the figure it is clear that
Fx =F cos 60° =20 cos 60° =10 kN (to the left)
Fy= F sin 60° =20 sin 60° = 17.32 kN (downward)
