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salantis [7]
3 years ago
8

A book is dropped from a window. It takes 5 seconds to reach the ground. What is its velocity after 2 seconds? What’s the veloci

ty at the time when it hits the ground?
Physics
1 answer:
ira [324]3 years ago
3 0

Answer:

Explanation:

Initial velocity is 0. In the equation v = v0+at where v0 is the initial velocity of 0, we only have to fill in -9.8 for a and 2 for t to get the velocity after 2 seconds -19.6 m/s; after 5 seconds, when it hits the ground, a = -9.8 and t = 5 to give a velocity of -49 m/s. Gravity pulls down everything at the same rate, it doesn't matter whether we drop a feather or an elephant from the window!

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A point charge q1 = 3.0 µC is at the origin and a point charge q2 = 6.0 µC is on the x axis at x = 10 m.
UkoKoshka [18]

Answer:

a) 1.6 mN  b) -1.6 mN  c) -1.6 mN  d) 1.6 mN

Explanation:

The electrostatic force between 2 point charges, obeys the Coulomb's Law, that can be expressed as follows:

F₁₂ = k*q₁*q₂/(r₁₂)² (in magnitude)

The direction of the force, is along the  line that joins the  charges (along the x axis) and as q₁ and q₂ are of the same sign, aims away from both charges.

a) So, for the force on q₂, we have:

F₁₂ = 9*18*10⁻⁵ N = 1.6 mN (positive as it is aiming in the positive x direction)

b) The force on q1, according to Newton's 3rd Law, is just equal and opposite to the one on q2:

F₂₁ = (-9*18*10⁻⁵) N = -1.6 mN (towards the negative x direction, away from q1)

c) If q₂ were -6.0 μC, the force will be the same in magnitude, but as now both charges have different signs, they wil attract each other, so the direction of the forces will be exactly the opposite to the first case:

F₁₂ = -1.6 mN (going towards the origin, where q₁ is located)

F₂₁ =  1.6 mN (going in the positive x direction, towards q₂)

6 0
3 years ago
Read 2 more answers
How to solve <br>9.8 = (x-0) =?<br> 4.3​
Nadya [2.5K]
You want to know how to solve it?
7 0
3 years ago
At this radius, what is the magnitude of the net force that maintains circular motion exerted on the pilot by the seat belts, th
Ainat [17]

Answer:

Fc=5253 N

Explanation:

Answer:

Fc=5253 N

Explanation:

sequel to the question given, this question would have taken precedence:

"The 86.0 kg pilot does not want the centripetal acceleration to exceed 6.23 times free-fall acceleration. a) Find the minimum radius of the plane’s path. Answer in units of m."

so we derive centripetal acceleration first

ac (centripetal acceleration) = v^2/r

make r the subject of the equation

r= v^2/ac

 ac is 6.23*g which is 9.81

v is 101m/s

substituing the parameters into the equation, to get the radius

(101^2)/(6.23*9.81) = 167m

Now for part

( b) there are two forces namely, the centripetal and the weight of the pilot, but the seat is exerting the same force back due to newtons third law.

he net force that maintains circular motion exerted on the pilot by the seat belts, the friction against the seat, and so forth is the centripetal force.

Fc (Centripetal Force) = m*v^2/r  

So (86kg* 101^2)/(167) =

Fc=5253 N

4 0
3 years ago
Listed following is a set of statements describing individual stars or characteristics of stars. Match these to the appropriate
Oksana_A [137]

Answer:

Red giant or super giant → very cool but very luminous

                                      → found in the upper right of the H-R diagram.

Main sequence →The majority of stars in our galaxy

                        → Sun, for example

                        → a very hot and very luminous star

White dwarfs → very hot but very dim

                     → not much larger in radius than earth  

Explanation:

Giant:

When the stars run out of their fuel that is hydrogen for the nuclear fusion reactions then they convert into Giant stars.That's why they are very cool. Giant stars have the larger radius and luminosity then the main sequence stars.

Main Sequence:

Stars are called main sequence stars when their core temperature reaches up to 10 million kelvin and their start the nuclear fusion reactions of hydrogen into helium in the core of the star. That is why they are very hot and luminous. For example sun is known as to be in the stage of main sequence as the nuclear fusion reactions are happening in its core.

White dwarfs:

When the stars run out of their fuel then they shed the outer layer planetary nebula, the remaining core part that left behind is called as white dwarf. It's the most dense part as the most of the mass is concentrated in this part.

6 0
3 years ago
How many significant digits are in the number 0.010?
Soloha48 [4]
There a two significant digits

explanation:
Trailing zeros after a decimal point count if preceded by a non-zero value. Example: 0.01 one significant figure, 0.010 two significant figures, 0.0100 three significant figures.

6 0
3 years ago
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