E Pentaksiran Fizik F4 2021

Firs law of Kepler?

• None

• The orbit of planet is an ellipse with the Sun at one of the two foci

• The radius vector of a planet sweeps over equal areas in equal time intervals of time.

• The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit

What is the third law of Kepler

• A planet travels in an ellipse with the Sun at one focus.

• The square of the period of any planet is proportional to the cube of the semimajor axis of its orbit.

• The radius vector of a planet sweeps over in equal area in aqual interval of time.

• None

The escape velocity of a sphere of mass m from earth having mass M and radius R is given by

•  $\sqrt{\frac{GM}{R}}$  

•  $\sqrt{\frac{2GM}{R}}$  

•  $\sqrt{\frac{GM}{2R}}$  

•  $\sqrt{\text{4GM/R}}$  

The escape velocity from the earth is about 11 km/second. The escape velocity from a planet having twice the radius and the same mean density as the earth, is

• 11km/s

• 5.6km/s

• 22km/s

• 55.6km/s

Force of gravity is inversely proportional to

• Mass
• Weight
• Distance
• Time

Calculate the gravitational force between two objects when they are 0.750m apart. Each object has a mass of 5.00kg.

• 2.96x10^-7N

• 3.00x10^-6N

• 2.22x10^-9N

• 2.23x10^-8N

Two objects are attracted to each other with 36 N of gravitational force.
What would the force between them be if the distance between them were doubled?

• 9
• 18
• 72
• 144

Calculate the escape velocity of a satellite in an orbit 300 km above Earth’s surface. Given G = 6.67 x 10^-11 N m^2 kg^-2, radius of earth is 6370 km and mass of the earth is 5.97 x 10^24 kg.

• 7.73 km s^-1

• 10.9 km s^-1

• 36.4 km s^-1

• 244 km s^-1

• A

• B

• C

• D

• A

• B

• C

• D