It's not so much a "contradiction" as an approximation. Newton's law of gravitation is an inverse square law whose range is large. It keeps people on the ground, and it keeps satellites in orbit and that's some thousands of km. The force on someone on the ground - their weight - is probably a lot larger than the centripetal force keeping a satellite in orbit (though I've not actually done a calculation to totally verify this). The distance a falling body - a coin, say - travels is very small, and over such a small distance gravity is assumed/approximated to be constant.

3 0

2 years ago

Which of the following material offers the lowest resistivity?

Yuki888 [10]

Lower resistivity means higher conductivity: among these materials, the best conductor is silver, therefore it must be the material with lowest resistivity among those. We can also have a look at the value of resistivity of the different materials listed in the problem, to check our answer. The resistivities of the materials are the following:
Wood: $1.00\cdot 10^{3} \Omega \cdot m$
Salt water: $2.00\cdot 10^{-1} \Omega \cdot m$
Silver: $1.59\cdot 10^{-8} \Omega \cdot m$
Lead: $2.20\cdot 10^{-7} \Omega \cdot m$
<span>We see that the material with lowest resistivity among those is silver, therefore the correct answer is silver.</span>

7 0

2 years ago

Read 2 more answers

To Mr. H's disgust, a 450-g black crow is raiding the recently-filled bird feeder. As Mr. H runs out the back door with his broo

bagirrra123 [75]

Answer:

Actually it's 2.50 m/s, sorry

Explanation:

It is solved by using momentum conservation equation

combined mass of crow and feeder = 450+670=1120 gm

let the recoil speed of feeder be v m/s

Then applying momentum conservation we get;

1120×1.5 = 670×v

v= 2.50 m/s

the speed at which the feeder initially recoils backwards = 2.50 m/s

5 0

3 years ago