Other Physics Answers

3. A 5kg block is connected to a 3kg block by means of a string that passes over a pulley. Find the (a) unbalanced force, (b) acceleration of the blocks, and (c) tension in the string. Assume that the pulley and the surfaces are frictionless.

 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.

A rod has a cross-sectional area of 25 cm². One end of the rod is heated until a steady state of heat conduction was established. The unheated end of the rod is in contact with 525 g of water. The temperature of water increases by 1 C after 3.0 min. (a) At what rate is heat transferred by conduction? It was found out that the temperatures between two points in the rod differs by 2 C°. The two points are 12.5 cm apart. (b) What is the thermal conductivity of the rod?

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°

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

A man of mass 50kg ascends a flight of stairs 5m high in 5 seconds. If accelerator due to gravity is 10m-2. Calculate the power expended.