Mid term exam Mr. Boula

A planet has a mass of 5.98 x 10²⁴ kg and a radius of 6378 km. If G = 6.67 x 10^-11 N.m²/kg² , so the intensity of the planet's gravitational field at a point that lies at a distance of 36000 km from the planet's surface equals …………………… N/Kg

• 22.2 x 10^-4

• 22.2 x10^-2

• 22.2 x 10²

• 94.1 x 10⁵

8. The opposite graph represents the relation of gravitational field strength (g) at different points around a planet of mass M versus the reciprocal of the squared distance between each point and the planet's center, so the planet's mass (M) equals ………………………….. 
                                (Take: G=6.67 x 10^-11 N.m²/kg²) 

• 4 x 10¹⁴ Kg

• 6 x 10¹⁴ Kg    

• 4 x 10²⁴ Kg   

• 6 x10 ²⁴ Kg

A racing car of mass 905 kg moves in a horizontal circular path of radius 517 m.  If the force that retains the circular motion of the car equals 2140 N, the tangential velocity of the car is approximately …………m/2

• 20

• 35

• 40

• 50

If the centripetal force that keeps a car moving in a horizontal circular roadway of  radius 500 m equals 0.08 of the car's weight, the maximum speed by which the car can move on that road equals … m/s                            (take g = 10  m/s²)

• 10

• 20

• 40

• 400

In the display window of a toy store at the mall, a battery-powered plane is suspended from a string and flying in a horizontal circle. The 631 gram plane makes a complete circle every 2.15 seconds. The radius of the circle is 0.95 m. Determine the centripetal force acting upon the plane? 

• 5.13 N

• 6.45 N

• 5.7 N

• 10.3 N

if the distance between the centers of two bodies is doubled, the mutual attraction force between them will be ... 

• doubled

• halved

• quartered

• quadrupled

A 72kg astronaut floats at a distance of 10 m from a 50000 kg spacecraft. What is the gravitational force of attraction between the astronaut and spacecraft?
                                                                        (Take: G=6.67 x 10^-11N.m²/kg²)

• 2.4 x 10^-6 N

• 2.4 x 10^-5 N

• zero

• 2.4x 10⁵N 

If the tangential velocity with which a body moves in a horizontal circular path is 7 m/s and the body completes 4 turns through two minutes, the radius of the circular path equals …………… m

• 66.8

• 25.2

• 33.4

• 30.6

A body rotates in a horizontal circular path with a centripetal acceleration of 10 m/s², so if the tangential velocity of that body gets doubled and the radius of its circular path gets halved, the centripetal acceleration of the body becomes …. m/s² 

• 5

• 20

• 40

• 80

The opposite graph represents the relation between the centripetal acceleration (a_c) with which a body should move in a horizontal circular path and the square of the linear velocity (v²)  with which the body moves, so the radius  of this circular path equals ………………….. m

• 100

• 175

• 200

• 250