Which of the following statements is true? give all correct answers

a) if the acceleration of a body is constant in a given inertial reference frame (a frame of reference with constant velocity), it is constant in all other inertial reference frames.
b) in projectile motion when air resistance is negligible it is never necessary to consider 3d motion rather than 2d motion.
c) if the elevation angle of a projectile at launch increases, its range decreases.
d) it is possible to be accelerating if you are traveling at a constant speed.
e) you are driving a distance directly behind a pickup truck, going at the same speed as the truck. a crate falls from the bed of the truck to the road. your car will hit the crate before the crate hits the road if you neither brake nor swerve.
f) if the elevation angle of a projectile at launch increases, its time-of-flight until impact also increases.

it doesn't. it was imagined up in the middle ages.

e/c, where e is its total energy

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.