In the letter style, all components of the letter begin flush with the left margin. a. modified block b. block c. modified semi-block d. all of the above

Explanation:

Modified block letter style is a format letter where all text is aligned left, expect the author's address, date and closing.

Block letter style is a format letter where absolutely all text is aligned to the left margin, with no exceptions.

Modified semi-block letter style. In this format, elements from the header and closing are aligned away from the left margin and the body text is justified to the left.

As you can observe from each definition, the one that completes the given statement is block, because in block letter style, all components are aligned to the left margin.

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.