The center of mass of a cow and the center of mass of a tractor are 208 meters apart. The magnitude of the gravitational force of attraction between these two objects is calculated to be 1.8 × 10-9 newtons. What would the magnitude of the gravitational force of attraction be between these two objects if they were 416 meters apart?
A.
1.62 × 10-9 newtons
B.
3.6 × 10-10 newtons
C.
9 × 10-10 newtons
D.
4.5 × 10-10 newtons

Choice: D.

Explanation:

Newton’s Law of Universal Gravitation

It states that objects attract each other with a force that is proportional to their masses and inversely proportional to the square of the distance between them.  The formula is:

Where:

m1 = mass of object 1

m2 = mass of object 2

r     = distance between the objects' center of masses

G   = gravitational constant:

The center of mass of a cow is at a distance of r=208 m from the center of the mass of a tractor. The gravitational force of attraction is . It's required to find the new force of attraction F' if the distance was r'=416 m.

It can be noted that r'=2r. If the distance is doubled, the new force is:

Substituting the original value of F:

Operating:

Choice: D.

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards

it is b. absorbs thermal energy