Physics Answers

a.    You came across a picture of three coplanar forces acting at a point, P. The first force is 200N and acting at 20° to the horizontal; the second 400N and acting at 165° to the horizontal; the third 500N acting at 250° to the horizontal. Draw what you saw in the picture using an appropriate scale. Use protractor for the angles.                                                                              

                                                                                                      AP [5 Marks]

b.   With the information in a); determine by resolution of forces:

i.      The magnitude of the resultant of the three coplanar Forces.

ii. The direction of the resultant of the three coplanar forces.

The moon is 3.9 × 105 km from Earth's center and 1.5 × 108 km from the Sun's center. The masses of earth and the sun are 6.0 × 1024 kg and 2.0 × 1030 kg, respectively. Find the ratio of the gravitational fields due to Earth and the Sun at the center of the Moon.

Show solution

The spring oscillates to the other end. The amplitude is 3.5m, k = 1.2, and angular frequency is = 4.3 . Solve the wave speed.

Block 1 of mass m1 = 2 kg is placed on block 2 of mass m2 = 3 kg which is then placed on a table. A string connecting block 2 to a hanging mass M passes over a pulley attached to one end of the table, as shown in Fig. 1. The mass and friction of the pulley are negligible. The coefficients of friction between block 1 and block 2 are μ1s = 0.2, μ1k = 0.1 and between block 2 and the tabletop air μ2s = 0.3, μ2k = 0.15. Draw the complete free body diagram of the system and determine the largest value of M for which the blocks can remain at rest.

At the same rotational speed and coefficient of static friction between sock and the drum, would a sock of twice the mass slide down the wall? Explain your answer

A long distance swimmer is able to swim in calm water at 4.0 km / h. She wants to try swimming from Port Angeles, Washington, directly north to Victoria, British Columbia, a distance of 50 km. An ocean current crosses the Strait of Juan de Fuca from west to east at 3.0 km / h. In what direction (relative to North) must you swim to cross a straight line between the two cities?

A blast pump is pumping 5000 tons of water in one hour. A leakage occurs in the supply pipe and stream of water is coming out in a vertical direction with an initial velocity of 45 m/s and takes 3.5 seconds to reach its maximum height.

(a) Calculate the maximum height that water jet will reach.

(b) Draw the velocity - time graph for vertical motion of the water jet and with the help of graph justify the answer of part (a).

(c) With what velocity the water will touch the ground when it returns back om its maximum height?

An intensity of a sound wave is measured to be 1.87×10⁴ W/m² at position A, 120 m away from the source of this sound. A worker at position B, 308 m away from the source hears the sound.

What is the energy of the sound wave at position B, if that sound lasts 5 minutes?

Select one:

1.0×10¹² J

 1.69×10¹⁰ J 

 2.8×10⁸ J

 8.4×10⁹ J

L (meters) mass Time for 30 oscillations Period T (seconds) T² g = 39.44L/T2

Average value of g = __________

QUESTIONS:

1) From your data what effect does changing the mass have on the period (for a

given value of the length L)?

2) What role, if any, does air resistance have on your results? Explain your

reasoning.

3) Would you conclude that Galileo was correct in his observation that the

period of a simple pendulum depends only on the length of the pendulum?

4) On the moon, the acceleration due to gravity is one-sixth that of earth. That is

gmoon = gearth /6 = (9.8 m/s2

)/6 = 1.63 m/s2

.

What effect, if any, would this have on the period of a pendulum of length L?

How would the period of this pendulum differ from an equivalent one on earth.

In a centrifugal compressor suction and delivery pressure are 100 kpa and 550 kpa respectively .The compressor draws 15m3/kg .Find increase in internal energy per kg of air