Sure let me download it rn
        
             
        
        
        
Answer:
COMPLETE QUESTION
A spring stretches by 0.018 m when a 2.8-kg object is suspended from its end. How much mass should be attached to this spring so that its frequency of vibration is f = 3.0 Hz?
Explanation:
Given that,
Extension of spring
x = 0.0208m
Mass attached m = 3.39kg
Additional mass to have a frequency f
Let the additional mass be m
Using Hooke's law
F= kx
Where F = W = mg = 3.39 ×9.81
F = 33.26N
Then,
F = kx
k = F/x
k = 33.26/0.0208
k = 1598.84 N/m
The frequency is given as
f = ½π√k/m
Make m subject of formula
f² = ¼π² •(k/m
4π²f² = k/m
Then, m4π²f² = k
So, m = k/(4π²f²)
So, this is the general formula, 
Then let use the frequency above 
f = 3Hz
m = 1598.84/(4×π²×3²)
m = 4.5 kg
 
        
             
        
        
        
Answer: Bohr's model (1913)
   Niels Bohr improved Rutherford's model. Using mathematical ideas, he showed that electrons occupy shells or energy levels around the nucleus. The Dalton model has changed over time because of the discovery of subatomic particles.
Bohr's model (1913) 
   Niels Bohr improved Rutherford's model. Using mathematical ideas, he showed that electrons occupy shells or energy levels around the nucleus. The Dalton model has changed over time because of the discovery of subatomic particles
   Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass.
   John Dalton
The idea that everything is made of atoms was pioneered by John Dalton (1766-1844) in a book he published in 1808. He is sometimes called the "father" of atomic theory, but judging from this photo on the right "grandfather" might be a better term.
 
Explanation:
 
        
             
        
        
        
Answer: Uses of clay are as follows.
Explanation:
Clay is a type of soil whose sediment consists of particles smaller than slit, that is, around 0.004 mm. This means that particles of a clay are very small.
A clay is soft and can be molded to different shapes easily.
Some uses of clay are as follows.
- It is used to make ceramics.
- It is used to make pottery like clay pot to store water in summers.
- It is also used to make tile and china dishes.