Question

Why is it easier for you to float in salt water than in freshwater?
A.)Salt water has higher density
B.)Fresh water has higher density
C.)Salt water has less density
D.)Salt water has less current

Answer 1

Hint: Use formula of density to understand this concept. Use mass and density relation. Use buoyant force concept. To visualize this concept use daily life examples such as the ocean, lake etc.

Step by step solution:
If you have ever floated on an ocean and river, then you will feel that floating on the ocean is much easier than the river. River has fresh water or you can say that it has less amount of salt present. But the ocean has a lot of salt present in it. So concentration in the ocean is much higher than concentration in the river.

Thus when salt is dissolved in water, like ocean water, salt which was dissolved adds mass to the mass of water per unit of volume and makes the water denser than it would be without salt.

Because objects flow better on a dense surface, they float better in saltwater than freshwater.
We can also understand this concept by using formula.
Formula of density in terms of mass and volume.

$density=\dfrac{mass}{volume}$

As you can see in the above equations density is directly proportional to mass and inversely proportional to volume. It means that adding mass in a water makes that water denser as mass directly proportional to mass. If our body weight is lighter than the density of seawater then the body is more buoyant in seawater.

Correct option is - (A)

Note: Do not get confused between option (A) and option (C). Mass and weight are two different concepts. Students can use buoyant force concepts also. Do not get confused between buoyant force and buoyancy force. Both are the same. It is an upward thrust, force exerted by fluid in upward direction. Which is responsible for the float body.