Answer:(a)10 ft/s
(b)4 ft/s
Explanation:
Given
height of light 
height of man

From diagram



differentiate both sides

Tip of shadow is moving at the rate of

(b)rate at which length of his shadow is changing
Length of shadow is 
differentiating w.r.t time


Answer:
NH₃
Explanation:
The compound that is covalent from the given choices is NH₃.
Covalent compounds are usually formed between two atoms with similar values of electronegativities such that the difference is very small or zero.
- This bond type involves the sharing of electrons between two atoms with similar electronegativities.
- Nitrogen and hydrogen forms stable configuration that are isoelectronic with noble gases by sharing their valence electrons.
- The 3 hydrogen electrons are enough to make nitrogen isoelectronic with neon.
- Also, the nitrogen with 3 lone pairs of electrons provides the bonding hydrogen with needed electrons to attain a structure similar to helium.
Answer:

Explanation:
Given:
- charge on the alpha particle,

- mass of the alpha particle,

- strength of a uniform magnetic field,

- radius of the final orbit,

<u>During the motion of a charge the magnetic force and the centripetal forces are balanced:</u>


where:
v = velocity of the alpha particle



Here we observe that the velocity of the aprticle is close to the velocity of light. So the kinetic energy will be relativistic.
<u>We firstly find the relativistic mass as:</u>



now kinetic energy:



Answer:
d
Explanation:
Solution:-
- The Quantity of theory of money states:
M * V = P * Y
Where,
M = Money supply
V = Velocity of money exchange
P = The price level
Y = Real GDP
- By re-arranging the formula and solving for "V" we have:
V = P*Y / M
- The expression on right hand side increases if exchange of dollars increases.
According to Hooke's Law formula. The force is proportional to the displacement of the spring. I believe