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1. When determining whether a rigid body is in equilibrium, the vector sum of the gravitational forces acting

on the individual particles of the body can always be replaced by a single force acting at:

• a point on the boundary

• the geometrical center

• the center of mass

• the center of gravity

• any of the above

2. A 7 m- long beam of negligible mass is hanged horizontally and is supported at each end by vertical cables. A

person of unknown weight is sitting on it somewhere between the cables. The tension in the left cable is 300 N,

and that in the right cable is 400 N. How far is the person sitting from the left cable?

• 3 m

• 4 m

• 7 m

• 6 m

• 5 m

Find the tension T2 in the left hand rope shown in the figure, for the case  where 

 $\theta_2=60\degree,\ \ \theta_3=30\degree$  and W= mg = 50 N.

• 50 N

• 100 N

• 43 N

• 87 N

• 29 N

A 1000- N block is suspended as shown. The beam AB is weightless and is hinged to the wall at A. The beam is 10 m long. The 4-m-long horizontal cable is attached to the midpoint of the beam AB from a point 3 m above point A on the wall. Find the tension in the horizontal cable,

• 667 N

• 2000 N

• 375 N

• 2670 N

• 1000 N

A rectangular, uniform chest of drawers 4- feet high and 3-feet wide is standing on a ramp as shown. There is enough friction so that it cannot slide. What is the largest angle q for which the chest will not topple over?

• 36.9^o

• 53.1^o

• 41.4^o

• 48.6^o

The magnitude of the acceleration of gravity for a planet in orbit around the Sun is proportional to:

• the mass of the planet

• the mass of the Sun

• the distance between the planet and the Sun

• the reciprocal of the distance between the planet and the Sun

• the product of the mass of the planet and the mass of the Sun

A starship of mass m is traveling between a pair of binary stars that are a distance R apart. The mass of star 2 is exactly twice the mass of star 1. How far from star 1 will the gravitational force on the starship be equal to zero?

Express the answer in terms of R.

• 1.41R

• 2R

• R/0.41

• R/2

• R/2.41

The acceleration due to gravity on the planet Krypton is 3 times of that on the Earth. The planet’s radius is 2 times

that of the Earth. What is this planet's mass in terms of the mass of the Earth, Me, ?

• 0.75 Me

• 1.33 Me

• 12.0 Me

• 4.0 Me

• 0.08 Me

One of Saturn's moons is in an orbit around Saturn. The moon’s mean orbital radius is 1.86 x 108 m and its period for revolving around Saturn is 22.7 hours. What is the mass of Saturn?

• 3.75 x 10²⁶ kg

• 2.29 x 10²⁶ kg

• 4.59 x 10²⁶ kg

• 6.81 x 10²⁶ kg

• 5.69 x 10²⁶ kg

The Moon takes 27.2 days to revolve around the Earth in an orbit whose radius Rm is about 383,000 km. What would be the approximate orbital radius for an Earth satellite that circles the Earth exactly once per day.

• 43,000 km

• 25,000 km.

• 2700 km

• 3.4x106 km.

• 50,000 km