Answer:
Helium has many unique properties: low boiling point, low density, low solubility, high thermal conductivity and inertness, so it is use for any application which can explioit these properties. Helium was the first gas used for filling balloons and dirigibles
Answer: Marie Curie's work with Becquerel made her more curious and prompted her to research and experiment with radioactivity.
Explanation:
Henri Becquerel was a French physicist who in 1896 discovered a new property of matter (which was later called <u>radioactivity</u>). This was accidentally observed when Becquerel found out that uranium salt was spontaneously emitting some kind of rays that went through different substances and were able to veil even a photographic film.
Then Marie Curie and her husband Pierre Curie carried out more experiments to study, in a <u>quantitative way</u>, the radiation emitted by the salts Becquerel studied <u>cualitatively,</u> and other salts that contained uranium. During this process they found other radioactive substances, such as: thorium, polonium and radium.
For that reason, the three of them were awarded the Nobel Prize in Physics in 1903 for their discovery of radioactivity.
Answer:
Yes a body moving with a constant speed has an acceleration. When an object travel in a circle with a constant speed it's direction keeps changing as a result velocity changing but it works at the centre of the circle therefore acceleration acts at the centre of the circle.
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- Velocity is the distance travelled by an object in a unti time with a specific direction . It is a vector quantity.
- Velocity = Displacement/time
- Ways in which velocity can be change -
- By changing speed
- By changing Direction
- Acceleration is the rate. change of velocity
- Acc = V - U /t
- It is also a vector quantity
- Si unit of velocity = M/S
- Si unit of acceleration = M/S^2
- Average velocity = V + u /2
- U = Initial velocity
- V = Final velocity
- acc = acceleration
- The initial velocity of an object at rest is 0
- The final veloctiy of an object after rest is 0
R = D/2 = 4.0 / 2 = 2 m
a = V² / R = 2,8² / 2 = 7.84 / 2 = 3.92 m/s²