A fisherman and his young son are in a boat on a small pond. Both are wearing life jackets. The son is holding a large helium filled balloon by a string. Consider each action below independently and indicate whether the level of the water in the pond, Rises, Falls, is Unchanged or Cannot tell.
Answers either R-Rises, F-Falls, U-Unchanged, C-Cannot Tell

(a)The fisherman knocks the tackle box overboard and it sinks to the bottom.

(b)The son gets in the water, looses his grip on the string, letting the balloon escape upwards.

(c)The fisherman lowers the anchor and it hangs one foot above the bottom of the pond.

(d)The son pops the helium balloon.

(e)The fisherman lowers himself in the water and floats on his back.

(f)The fisherman fills a glass with water from the pond and drinks it.

(a) U

(b) R

(c) R

(d) R

(e) U

(f)  U

Explanation:

According to law of flotation, a floating body will displace the same amount of liquid as the volume of the body itself.

(a) The level of water remains unchanged because the the tackle box weight/volume remains unchanged whether it is on the surface or beneath the water.

(b) The floating balloon must have been holding part of the weight of the son because it is against gravity. Hence, the weight of the son will increase with the loss of the balloon. This will lead to more water volume being displaced and hence, a rise in the level of water in the pond.

(c) The anchor must have been holding some of the weight of the boat including those in the boat. When the anchor is lowered, more weight of the boat is released into the pond and more water volume is displaced. Hence, the water level in the pond rises.

(d) When the balloon is popped, the weight of the son increases because their is no upthrust force opposing his weight. Hence, more water is displaced and the level rises.

(e) When the fisherman lowered himself in water, he will still be displacing his own weight which remains unchanged. Hence the level of water also, remains unchanged.

(f) Since the volume of water is just been transferred from the pond to the man who happens to still be in the pond. The level of water remains unchanged.

the small 0.38-kg slider is known to move from position a to position b along the vertical-plane slot. determine (a) the work done on the body by its weight and (b) the work done on the body by the spring. the distance r = 0.70 m, the spring modulus k = 154 n/m, and the unstretched length of the spring is 0.53 m

explanation:

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