Chapter 4, Problem 81A

To determine

Magnitude of acceleration of combination of masses.

Answer to Problem 81A

Acceleration of combination of masses is $0.689{\text{ m/sec}}^2$

Explanation of Solution

Given :

Horizontal force $F=4.5\text{ N}$

Acceleration of first block $a=2.5{\text{ m/sec}}^2$

Mass of second block $m_2=4\text{ kg}$

Formula used :

The force is given by,

  $F=ma$

Where,

m is mass.

a is acceleration.

Calculation:

Let mass of the first block is $m_1$

Therefore,

  $4.5=m_1\times 2.5$

  $\begin{array}{c}{m}_1=\frac{4.5}{2.5}\\ =1.8\text{ kg}\end{array}$

Now, a second mass is dropped on first mass $m_2=4\text{ kg}$

Therefore, total mass

  $\begin{array}{c}m=m_1+m_2\\ =1.8+4\\ =5.8\text{ kg}\end{array}$

Now, again using Newton’s law,

  $4=5.8\times a$

  $\begin{array}{c}a=\frac{4}{5.8}\\ =0.689{\text{ m/sec}}^2\end{array}$

Conclusion:

Therefore, acceleration of combination of masses is $0.689{\text{ m/sec}}^2$