From the basic "heat lost by hot object=heat gained by colder object" principle, we have

m1c1ΔT1=m2c2ΔT2

where m1= 1kg

m2=4kg

c1=900J/kg k

c2=4200J/kg k

With this information at hand we have

m1c1(90-T)=m2c2(T-25)

after substituting the given values we can find that

T=28.3^{0}c

**Answer:**

w=255

**Explanation:**

The change in internal energy is given by the first law:

ΔE = Q - w

where ΔE is the change in internal energy of the system

q is the heat added to the system

w is the work done *by* the system on the surroundings

So, for the first phase of this process:

ΔE = Q - w

Q=160J

w=309J

ΔE = 160J - 309J = -149J

To bring the system back to its initial state after this, the internal energy must change by +149J (the system myst gain back the 149 J of energy it lost). We are told that the system loses 106 J of heat in returning to its initial state, so the work involved is given by:

ΔE = Q - w

+149J = -106J - w

255J = -w

w = -255J

When you pull a magnet off a refrigerator door, the potential energy increases because the farther the two charged objects move apart, the more charge they get.

**Explanation:**

The relationship between the wavelength and the potential difference V is given by :

**Putting the values of known parameters,**

**(a)**

**(b)**

**Hence, this is the required solution.**

C. The bowling ball and the bicycle

p = mv

P of bike = 12x5 = 60

P of rock = 2x20 = 40

P of ball = 5 x 10 = 60