Forces and Newton’s Laws: Question 6

Worked solution

Step 1: Identify the forces and their directions

Three forces act on the crate along the same straight line:

• $20\text{ N}$ to the right
• $8\text{ N}$ to the left
• $5\text{ N}$ to the left

Step 2: Combine forces acting in the same direction first

The two leftward forces act along the same line and in the same direction, so they add together:

$8\text{ N} + 5\text{ N} = 13\text{ N to the left}$

Step 3: Find the resultant of the two opposing totals

Now combine the $20\text{ N}$ rightward force with the $13\text{ N}$ leftward total. Since these act in opposite directions along the same line, subtract the smaller from the larger:

$\text{Resultant force} = 20\text{ N} - 13\text{ N} = 7\text{ N}$

Because the rightward force ($20\text{ N}$) is bigger than the total leftward force ($13\text{ N}$), the resultant acts to the right.

Why the other options are wrong

Final answers

• Resultant force $=$ $7\text{ N}$ to the right, option B