Topic Menu

Cyber-chess a chess instruction site

Vectors

Parallelogram of vectors - relative velocity


These questions may be done graphically.


Q1. Find the resultant of two forces 25 N and 20 N with an angle of 60° between them.

What is the angle between the resultant and the first force?

Resultant is 39 N

Angle between them is 26o


Q2. Find the resultant of two velocities, 40 m/s and 30 m/s, with an angle of 90° between them.

What is the angle between the resultant and the first velocity?

Resultant is 50 m/s

Angle between them is 37o


Q3. The resultant of two forces is 60 N. It acts at an angle of 30° to one of the forces, which has a magnitude of 45 N.

Find the magnitude of the second force.

Resultant is 31 N


Q4. Find the resultant of two forces (80 N and 40 N) acting at an angle of 120° to each other.

What is the angle between the resultant and the first force?

Resultant is 69 N

Angle between them is 30o


Q5. What is the actual course and speed of a ship which is heading due north at a speed of 12 km/h, across a tide running due west at 5.0 km/h?

Speed is 13 km/h

Course is 23o W of N


Q6. Find the resultant force on a stone in a catapult, if each of the two elastics in the catapult has a tension of 25 N and the angle between the elastics is 40°.

47 N


Q7. The pilot of an aircraft wishes to fly due north, but a wind of 45 km/h is blowing from the west.

If the aircraft can fly at 200 km/h in still air, in what direction must the pilot steer?

13o W of N


Q8. Find the time it takes a motor-launch, which moves through the water at 10 km/h, to travel across a river at right angles to the current which flows at 6.0 km/h.

The width of the river is 1.2 km.

9.0 minutes


Q9. Two cars leave a road junction at the same time.

Car A travels north at 45 km/h and car B travels east at 60 km/h.

Find the apparent speed and direction of B as seen by an observer in A.

75 km/h

53o E of S