Chapter 8.3, Problem 40PP

To determine

Forces exerted by the two supports.

Answer to Problem 40PP

Force exerted by support A is zero.

Force exerted by support B is $235.2\text{ N}$ .

Explanation of Solution

Given:

Length of the wooden plank $=4.5\text{ m}$

Mass of the wooden plank = $24\text{ kg}$

Consider support at one end to be support A and support under the centre of the board to be support B.

Known value:

Acceleration due to gravity = $9.8{\text{ m/s}}^2$

Formula used:

F = weight = mg

Where, m = mass of the plank

g = acceleration due to gravity

Figure:

  

Calculation:

• As it is clear from the figure that support B balances the wooden plank. So, support A exerts zero force on the plank.
• The upward force exerts on support B.

  $\begin{array}{l}F\text{=24}\times \text{9}\text{.8}\\ F\text{=235}\text{.2 N}\end{array}$

Conclusion:

• Force exerted by support A is zero.
• Force exerted by support B is $235.2\text{ N}$ .