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3 years ago

When t= 1 a stone B is thrown vertically upwards from ground level with speed 5ms (ii) find t when a and b collide

Physics

1 answer:

Ksju [112]3 years ago

5 0

Answer:

i don't know if this is good for you but

Explanation:

ignoring frictional air resistance (drag) the speed on return is the same as when it left the ground (5 m/s but in the opposite direction).

Note: this points out a good reason for not firing live bullets into the air..they will return somewhere and at the same speed.

However, if you take into account the atmospheric drag the reurn speed will be somewhat smaller (but in the case of a bullet, probably still lethal.) Drag depends on many factors and is difficult to calculate.

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Whose data did Kepler use to describe the motion of the planets?

Levart [38]

Answer:

Tycho Brahe

Explanation:

Tycho Brahe's accurate observations of planetary positions provided the data used by Johannes Kepler to derive his three fundamental laws of planetary motion.

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3 years ago

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An electron with charge −e and mass m moves in a circular orbit of radius r around a nucleus of charge Ze, where Z is the atomic

shepuryov [24]

Answer:

$v=\sqrt{\frac{kZe^2}{mr}}$

Explanation:

The electrostatic attraction between the nucleus and the electron is given by:

$F=k\frac{(e)(Ze)}{r^2}=k\frac{Ze^2}{r^2}$ (1)

where

k is the Coulomb's constant

Ze is the charge of the nucleus

e is the charge of the electron

r is the distance between the electron and the nucleus

This electrostatic attraction provides the centripetal force that keeps the electron in circular motion, which is given by:

$F=m\frac{v^2}{r}$ (2)

where

m is the mass of the electron

v is the speed of the electron

Combining the two equations (1) and (2), we find

$k\frac{Ze^2}{r^2}=m\frac{v^2}{r}$

And solving for v, we find an expression for the speed of the electron:

$v=\sqrt{\frac{kZe^2}{mr}}$

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3 years ago

How large is the acceleration of a 25 kg mass with a net force of 75 N applied horizontally to it?

Sveta_85 [38]

Answer:

Explanation:

F = ma

a = F/m

a = 75/25

a = 3 m/s²

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2 years ago

A driver in a 2000 kg Porsche wishes to pass to pass a slow-moving school bus on a four-lane road. What is the average power in

Kryger [21]

The average power is $3.0\cdot 10^6 W$

Explanation:

First of all, we calculate the work done to accelerate the car; according to the work-energy theorem, the work done is equal to the change in kinetic energy of the car:

$W=K_f -K_i= \frac{1}{2}mv^2-\frac{1}{2}mu^2$

where :

$K_f = \frac{1}{2}mv^2$ is the final kinetic energy of the car, with

m = 2000 kg is the mass of the car

v = 60 m/s is the final speed of the car

$K_i = \frac{1}{2}mu^2$ is the initial kinetic energy of the car, with

u = 30 m/s is initial speed of the car

Soolving:

$W=\frac{1}{2}(2000)(60)^2 - \frac{1}{2}(2000)(30)^2=2.7\cdot 10^6 J$

Now we can find the power required for the acceleration, which is given by

$P=\frac{W}{t}$

where

t = 9 s is the time elapsed

Solving:

$P=\frac{2.7\cdot 10^6}{9}=3.0\cdot 10^6 W$

Learn more about power:

brainly.com/question/7956557

#LearnwithBrainly

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4 years ago

An electromagnet is a device in which moving electric charges (current) in a coil of wire create a magnet. What’s one advantage

yan [13]

I think the correct answer from the choices listed above is option D. One advantage of using electromagnets in devices would be that electromagnets can <span>easily be turned on and off. Hope this answers the question. Have a nice day.</span>

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3 years ago

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