Final answer:
In projectile motion, when two objects are fired at angles that add up to 90° with the same speed, they will have the same range. The answer to which statement is true for projectiles fired at 60° and 30° is that their range will be the same.
Step-by-step explanation:
The question concerns the projectile motion of two objects fired from the same point, at the same speed, but at different angles of 60° and 30°, and which of the given options is true about their motions. In projectile motion, when two objects are projected at angles that add up to 90°, they will have the same range.
Therefore, the correct answer is that their range will be the same (b). This is because the complementing angles (30° and 60° in this case) result in the same horizontal component of the initial velocity when the speed is the same, thus leading to the same range. Maximum height, landing velocity, and time of flight will differ because they are all influenced differently by the vertical component of the initial velocity and the angle of projection.