15 guesting i think it not right
If the current takes him downstream we must find the resultant vector of the velocities:
Then if the river is 3000 m-wide the swimmer will have to pass:
1.3520747 · 300 = 4056.14 m t = 4056.14 m : 1 m/s
a ) It takes
4056.15 seconds ( 1 hour 7 minutes and 36 seconds ) to cross the river.
b ) 0.91 · 3000 =
2730 mHe will be 2730 m downstream.
Yes, that's correct. That's a big part of the reason why
the soap floats in water and the sponge sinks in it.
Answer:
The difference between a physical reaction and a chemical reaction is composition. In a chemical reaction, there is a change in the composition of the substances in question; in a physical change there is a difference in the appearance, smell, or simple display of a sample of matter without a change in composition. Although we call them physical "reactions," no reaction is actually occurring. In order for a reaction to take place, there must be a change in the elemental composition of the substance in question. Thus, we shall simply refer to physical "reactions" as physical changes from now on.
Explanation:
Physical changes are limited to changes that result in a difference in display without changing the composition. Some common changes (but not limited to) are:
Texture
Color
Temperature
Shape
Change of State (Boiling Point and Melting Point are significant factors in determining this change.)
Physical properties include many other aspects of a substance. The following are (but not limited to) physical properties.
Luster
Malleability
Ability to be drawn into a thin wire
Density
Viscosity
Solubility
Mass
Volume
Thermal energy is transforming, i think.
