# Homework Help: Explain why a dead body floats

1. Oct 27, 2007

### amritha_sish

1. A ball is thrown vertically upwards with a velocity of 49m/s. Calculate
a) The maximum height to which it rises
b) The total time it takes to return to the surface of the earth.

2. A certain force exerted for 1.2 seconds increases the speed of an object
from 1.8m/s to 4.2m/s. Later the same force is applied for 2 seconds. How
much does the speed change in 2 seconds?

3. A motorboat starting from rest on a lake accelerates in a straight line
at a constant rate of three metres per second square for 8 seconds. How
far does the boat travel during this time?

4. a) Why are double tyres provided at the rear wheels of a truck?

b) A man at the top of a tower throws an object horizontally
whereas he simply drops another. Will these two objects reach
the earth at the same time? Why?

c) Explain why a dead body floats, with its head immersed in
water?

2. Oct 27, 2007

### arildno

These questions are too difficult for me.
You have to give me some hints, that is: SHOW WHAT YOU HAVE DONE SO FAR!

3. Oct 27, 2007

### ace123

arildno is just kidding about it being too difficult. He just wants you to put in an effort to try to solve these problems otherwise he is just giving answers..

4. Oct 27, 2007

### iddheepak

A cadaver in the water starts to sink as soon as the air in its lungs is replaced with water. Once submerged, the body stays underwater until the bacteria in the gut and chest cavity produce enough gas -- methane, hydrogen sulfide, and carbon dioxide -- to float it to the surface like a balloon. (The buildup of methane, hydrogen sulfide, and other gases can take days or weeks, depending on a number of factors.) At first, not all parts of the body inflate the same amount: The torso, which contains the most bacteria, bloats more than the head and limbs. The most buoyant body parts rise first, leaving the head and limbs to drag behind the chest and abdomen. Since arms, legs, and the head can only drape forward from the body, corpses tend to rotate such that the torso floats facedown, with arms and legs hanging beneath it.

5. Oct 28, 2007

### amritha_sish

Thanx

Thanx for that explanation iddheepak.

Pl add on the first two Qns. They r too confusing.

6. Oct 28, 2007

### cristo

Staff Emeritus
As arildno has already told you, you must show your work before you will receive any help on these forums.

You should read the forum rules, specifically the homework help forum rules, available from an icon on the toolbar at the very top. That goes for people answering homework questions, as well as asking them.