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xxMikexx [17]
3 years ago
9

A radioactive isotope of potassium has a half-life of 20 minutes if a 40 g sample of this isotope is allowed to decay for 80 min

utes how many grams of the r
adioactive isotope will remain
Physics
1 answer:
FinnZ [79.3K]3 years ago
5 0

There will be 2.5g left.


Explanation:

80/20 = 4 half lives

40/2 = 20

20/2 = 10

10/2=5

5/2 = 2.5


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What type of energy travels through space as waves?
Nezavi [6.7K]

Answer:

electromagnetic energy

8 0
3 years ago
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A compact car, mass 664 kg, is moving at 19 km/h toward the east. What is the car's momentum in kg x m/s?
Natasha2012 [34]

Answer:

3504.4 kgm/s

Explanation:

First, convert km/hr to m/s:

19 km/hr x 1000m/1km x 1/60min x 1/60s = 5.28 m/s

p = mv

p = (664 kg)(5.28 m/s) = 3504.4 kgm/s

6 0
3 years ago
jack be nimble jack be quick jack jumped over the candlestick with a velocity of 5.0 m/s at an angle of 30.0 degrees to horizont
Mrrafil [7]

Answer:

No

Explanation:

The vertical component of Jack's initial velocity is:

5.0

⋅

sin

30

∘

=

5.0

⋅

1

2

=

2.5

m/s

With gravitational acceleration

9.8

m/s

2

, he will reach the highest point of his trajectory after:

2.5

9.8

≈

0.255

s

The average vertical component of his velocity in that

0.255

s

will be:

1

2

⋅

2.5

=

1.25

m/s

So the highest point of his trajectory will be:

0.255

⋅

1.25

≈

0.32

m

So he will pass approximately

7

cm

above the top of the candle.

The horizontal component of his velocity will be a constant:

5.0

⋅

cos

30

∘

=

5.0

⋅

√

3

2

≈

4.33

m/s

So Jack's trajectory will be substantially longer than it is high and he will spend little time anywhere near above the candle.

4 0
3 years ago
You push your little sister on a swing and in 1.1 minutes you make 54 pushes. what is the frequency of your swing? answer in uni
valentinak56 [21]
The frequency is the number of complete oscillations per second. One complete oscillation corresponds to 1 push. Converting the time into seconds:
t=1.1min \cdot 60 \frac{s}{min}=66 s
we can find the frequency of the swing:
f= \frac{54 pushes}{66 s}=0.81 Hz
3 0
3 years ago
How are energy, force, and the motion of objects related?
OLEGan [10]

Answer:

When two objects interact, each one exerts a force on the other that can cause energy to be transferred to or from the object. For example, when energy is transferred to an Earth-object system as an object is raised, the gravitational field energy of the system increases. This energy is released as the object falls; the mechanism of this release is the gravitational force. Likewise, two magnetic and electrically charged objects interacting at a distance exert forces on each other that can transfer energy between the interacting objects.

Explanation:

Even when an object is sitting still, it has energy stored inside that can be turned into kinetic energy (motion). ... A force is a push or pull that causes an object to move, change direction, change speed, or stop. Without a force, an object that is moving will continue to move and an object at rest will remain at rest.

5 0
3 years ago
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