Question

38. A block of wood weighs 160N and has a specific gravity of 0.60. To sink it in fresh water requires an additional downward force of: A. 54N B. 64N C. 96N D. 110N E. 240N

Answer 1

Question :-

→ A block of wood weighs 160 N and has a specific gravity of 0.60 . To sink it in fresh water requires an additional downward force of

(A) 54 N

(B) 64 N

(C) 96 N

(D) 110 N

(E) 240 N

Answer :-

→ Option (D) , nearly 110 N

To Find :-

→ Additional downward force required to sink that block.

Explanation :-

Given that :

• Specific gravity = 0.6 $\frac{kg}{m^3}$
• Force = 160 N

We know that

$\implies \boxed{\sf specific \: gravity \: = \frac{mass}{volume} } \\ \\ \implies \boxed{\sf force \: = mass \: (m) \times acceleration } \\ \\ \to \sf acceleration \: due \: to \: gravity \: (g) = 9.8 \: \frac{m}{ {s}^{2} } \\ \therefore \: \\ \to \sf 160 = mass \: (m) \times 9.8 \\ \\ \to \sf m = \frac{160}{9.8} \\ \: \\ \to \boxed{ \sf m \: = 16 .32 \: kg}$

Also ,we know that ,

$\implies \sf specific \: gravity \: = \frac{mass}{volume} \\ \\ \implies \sf \: volume = \frac{16.32}{0.6} \: {m}^{3} \\ \\ \implies \boxed{\sf volume \: = 27.2 \: {m}^{ 3} }$

Now ,let additional force is "x" ,

Additional force (x) will be -

•°• density of water = 1 $\frac{g}{cm^3}$

$\to \sf 1 = \frac{m + \frac{x}{9.8} }{27.2} \\ \\ \to \sf 27.2 = 16.32 + \frac{x}{9.8} \\ \\ \to \sf \frac{x}{9.8} = 10.88 \\ \\ \to \sf \: x = 106.62$

Additional force is about 110 hence

Option (D) is correct .

Answer 2

Answer:

110N

Explanation: