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almond37 [142]
3 years ago
8

How fast is a ball rolling if it contains 98 j of kinetic energy and has a mass of 4kg

Physics
1 answer:
zysi [14]3 years ago
4 0

Answer:

the ball is rolling 7m/s

Explanation:

Formula for kinetic energy: 1/2mv²

K = 1/2mv²

98 = 1/2(4)v²

98 = 2v²

49 = v²

√49 = v

7 = v

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Student swings a small rubber stopper attached to a string over her head in a horizontal, circular path. The string is 1.50 mete
harkovskaia [24]

Answer:

v = 18.84 m/s

Explanation:

Given that,

The length of the string, r = 1.5 m (it will act as radius)

The rubber stopper makes 120 complete circles every minute.

Since, 1 minute = 60 seconds

It means, its frequency is 2 circles every second.

Let we need to find the average speed of the rubber stopper. It can be calculated as follows :

v=\dfrac{d}{T}

d is distance, d=2\pi r and 1/T = f (frequency)

v=2\pi rf\\\\=2\pi \times 1.5\times 2\\\\=18.84\ m/s

So, the average speed of the rubber stopper is 18.84 m/s.  

4 0
3 years ago
a swimmer can swim in still water at a speed of 9.50 m/s. he intends to swim directly across the river that has a downstream cur
Doss [256]
Refer to the diagram shown below.

Still-water speed  = 9.5 m/s
River speed = 3.75 m/s down stream.

The velocity of the swimmer relative to the bank is the vector sum of his still-water speed and the speed of the river.

The velocity relative to the bank is
V = √(9.5² + 3.75²) = 10.21 m/s

The downstream angle is
θ = tan⁻¹ 3.75/9.5 = 21.5°

Answer:  10.2 m/s at 21.5° downstream.

7 0
3 years ago
Read 2 more answers
Why is an element considered a pure substance?
ElenaW [278]

Answer:

Explanation:

right

8 0
2 years ago
A. Besides protons, what other particles make up an atom? Write 2 - 3 sentences describing how the electrostatic force acts betw
vodomira [7]

<u>Answer:</u>

For a. Neutrons and electrons also form an atom.

For b. The element is oxygen which is a non-metal and will form a negative ion while forming ionic bond.

<u>Explanation:</u>

  • <u>For a:</u>

There are 3 subatomic particles which form an atom. These are neutrons, protons and electrons.

Neutrons carry no charge, protons carry positive charge and electrons carry negative charge. Neutrons and protons are present in nucleus and electrons revolve around the nucleus.

The energy which is present between neutrons and protons are nuclear energy and the energy which is present between electrons and protons are electrostatic energy.

  • <u>For b:</u>

In an element, number of protons is always equal to the number of electrons. The atomic number is equal to the number of protons or electrons. The element which has atomic number 8 is Oxygen.

The electronic configuration of this element is 1s^22s^22p^4

This element requires only 2 electrons to form a stable electronic configuration. An element which gains electron is considered as a non-metal and forms a negative ion because number of electrons increases.

3 0
3 years ago
A batter hits a baseball so that it leaves the bat with an initial speed of 60m/s at an initial angle of 42 with the horizontal
Elza [17]

Answer: 24.06°

Explanation:

So,we can say after t if it reaches height h then,

h = (37 sin 53)t - 1/2 * 9.8t^2 (as,vertical component of velocity is 37 sin 53)

Given t = 2s

So, h = 39.5m

And horizontal displacement will be

r = 37 cos 53 *2 = 44.52m

So,after 2s the baseball will be lying 39.57m

above its point of projection and 44.52m ahead of its point of projection.

Now.let the vertical component of velocity will become Vy after time 2s

So, Uy = 37 sin 53- 9.8* 2

or, U = 9.95m/s

And.horizontal component of velocity remains

constant i.e Vx = 37 cos 53 = 22.27m/s

So.magnitude of velocity after 2s is

Square root of (Vx^2 + Vy^2)= 24.4m/s

Making an angle of tan 22.27/9.95 = 24.06°

6 0
3 years ago
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