Answer:
I'm sorry I don't have a answer but I like your pfp
Q = m.s.Δt
Δt = Q /m.s
Here, Q = 30,000 J
m = 390 g
s = 3.9 J/g C
Substitute their values,
= 30,000 / 390 *3.9
= 30,000 / 1521
= -20 C (approx.) [-ve sign 'cause temperature is decreasing ]
In short, Your Answer would be Option D
Hope this helps!
Energy (<span>electromagnetic radiation</span>) is transferred through vibrations of electric and magnetic fields.
Answer:
Explanation:
Given
mass of book(m)=2.1 kg
height up to which book is lifted is (h)2.2 m
height of person 
Potential energy of book relative to ground=mgh
(b)PE w.r.t to person head =mg(h-h0)
work done by person in lifting box 2.2 m w.r.t floor
Word done =Potential Energy of box relative to floor=45.2 J
Reflecting telescopes are popular because they are more durable than a refracting telescopes.
There is a difference between these two types of telescopes, reflecting telescopes worked by reflecting light, they are also known as reflector and refracting telescopes worked by refracting light and they are also known as reflactor.
Reflecting telescopes also provides a good focus.
