Physics Answers

 If 10.0 g of ice at 0°C were added to 10 g of water at 20°C, what is the resulting temperature of the mixture?

 The heat exhausted to the heat sink by a heat engine is twice the mechanical work done. What is its efficiency?

Find the change in entropy when (a) 3.0 kg of boiling water changes to steam at 100°C. (b) 3.0 kg of water is heated from 20°C to 80°C, and (c) 2.0 kg of water at 30° are mixed with 5.0 kg of water at 75°C and the mixture allowed to reach equilibrium.

Calculate the dot product of C = (-2,-6)N and D = (-2,3)N.

Find a.b given that A= 3m and B = 5m at an angle of 45°

Two rods of brass and iron are fixed to a short cross bar. If the iron is 1m long, what must be the length of the brass rod that the distance AB between the free ends of the rods remain constant at all temperature? ( take αfe= 0.000012k, αbrass=0.000019k)

A long clothesline is stretched horizontally between two trees. While shaking this clothesline up and down near one end at the rate of 4 cycles per second, the wavelength is 1m. What is the speed of these waves? If the distant end is 10m apart how long does a wave pulse take to return to you

What will happen to the parameters of an optical fiber, when it is submerged into water i) numerical aperture and ii) acceptance angle?

1. A train, initially at rest, is subject to an acceleration of 32 m/s2.  How long will it take for that object to travel 3100 m?

Formula:  x = x0 + v0t + ½ at2

1. A bowling ball is at rest when it undergoes a constant acceleration of 13 m/s2 for 5 s.  How far will it have traveled during this time?

Formula:  x = x0 + v0t + ½ at2

1. What is the velocity of a dropped object after it has fallen for 2.0s?

Formula: v  = v0 +gt  

1. A ball is thrown straight up from the ground with an unknown velocity. It reaches its highest point after 3.5 s. With what initial velocity did it leave the ground? 

Formula:  v0  = v -gt

1. A  girl riding her bicycle accelerates from 0 m/s to 8 m/s in 5 seconds. What is the girl’s acceleration?

Formula: a  = (v – v0)

  t

1.  If a red Corvette, with an initial velocity of 14 m/s, accelerates at a rate of 32 m/s2 in  4 seconds, what will its final velocity, v (use Equation 3)be?

Formula:  v = v0 + at 

1. A cheetah accelerates from rest with a constant acceleration of 4 m/s2.  How far will it have moved after 12s? 

Formula: distance = speed x time

1. A rocket, moving with a constant velocity, travels 282 m in 21 s.  What is its velocity?

Formula:  speed = distance/time