Concurrent forces

A number of forces are concurrent when the lines of action of all of the forces

• occur at the same time

• pass through the same point

• are parallel to each other

• are not parallel to each other

When two forces act together on a force meter as shown, the reading on the meter will be

• 0 N

• 5 N

• 10 N

• 20 N

What will the readings be on these force meters?

• Left, 10 N; right pair 5 N each

• All 0 N

• Left, 20 N; right pair 10 N each

• All 10 N

Two (or more) forces can be added together to find the resultant force. The forces can be drawn "head to tail" - in any order. The resultant can then be drawn from the ________ of the first to the _______ of the last.

( just write the missing words )

The cables A and B are both in tension. The tension in B is much greater than in A. In what direction will the resultant force on the support fixing be acting?

• down and to the right

• up and to the right

• down and to the left

• up and to the left

The cables A and B are both in tension. The tension in B is much greater than in A. In what direction will the equilibrant (reaction) force provided by the support fixing be acting?

• down and to the right

• up and to the right

• down and to the left

• up and to the left

The tensile force in cable A is 10 N, in B the tensile force is 25 N. The force triangle showing the forces (F_A) and (F_B) and the sum of the forces (R) will be

• 
• 
• 
• 

Use the cosine rule ( a² = b² + c² - 2b.c.cos A ) to calculate the magnitude of the resultant force R

• R = 35.0 N

• R = 32.8 N

• R = 1079 N

• R = 19.3 N

Use the sine rule ( a / sin A = b / sin B = c / sin C ) and the magnitude of R = 32.8 N to calculate the direction of the resultant force relative to F_A.

• The resultant force R acts upwards and 15° CW from A

• The resultant force R acts upwards and 33° ACW from A

• The resultant force R acts upwards and 15° ACW from A

• The resultant force R acts downwards and 33° CW from A

The tensile force in cable A is 10 N, in B the tensile force is 25 N. The force triangle showing the forces (F_A) and (F_B) and the equilibrant (E) can be drawn as (choose all that apply):

• 
• 
• 
•