The scientist who discovered the two elements radium and polonium would be Marie Curie in 1898.
Hope this helps!
Question 2: i believe it's half life decay
question 3: relative dating
The amount of work which Sam does need to stop the boat is 784Joule if boat mass is 800kg and boat drift in 1.4m/sec.
We know that according to work-energy theorem, change in kinetic energy of the body from one speed to another is equivalent to amount of work done by all forces acting on the body.
So, here we can see that final speed of boat is =0m/sec since Sam need to stop it.
Initial speed of boat is 1.4m/sec.
Also, we know that kinetic energy is given by the below formula:
Kinetic energy=(1/2)mv²
where m is the mass of the body
and v is the speed of the body
Now, from work energy theorem, we get
=>W=(1/2)m
- (1/2)m
=>W=0-(1/2)×800×(1.4)²
=>W= - 400× 1.4 × 1.4
=>W = -400×1.96
=>W= -784Joule
Here negative sign denotes work has to done against the original motion of boat.
Hence, amount of work needs to be done by Sam is 784Joule.
To know more about work,visit here:
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Matter can be many things, but is mostly made of atoms. Atoms are small things that cannot be seen directly, as lights either passes through it or alters it. However, we know that atoms are made of 3 parts, those being the proton, neutron, and electron.
Protons have a positive electromagnetic charge.
Neutrons have no charge.
Electrons have a negative charge equal to the protons positive charge.
Protons and neutrons make up what's called the nucleus, which is orbited by the electrons.
Protons and neutrons also share another thing in common, that being their composition.
Until relatively recently, we thought that these were the smallest particles in the universe, and indestructible. However, modern discoveries have revealed that they are actually made of quarks and gluons.
These are actually indestructible, being part of the group that is elementary particles.
Answer:
Time to reach maximum height can be obtained from v=u+at
0=20+(−10)t
t=2s
s=ut+0.5at
2
=20(2)+0.5(−10)(2)
2
=20m
Thus, total distance for maximum height is 45 m
s=ut+0.5at
2
45=0+0.5(10)(t ′ )
2
t
′
=3s
Total time= 3+2= 5s
Explanation:
TAKE 22.0 IN PLACE OF 20 U WILL GET YR ANSWER
HOPE IT HELPS
