(12a) A boy kicks a rock off a cliff with a speed of 17.8 m/s at an angle of 55.3 above the horizontal. The rock hits the ground 5.72 s after it was kicked. How high is the cliff? (12b) What is the sp (12a) A boy kicks a rock off a cliff with a speed of 17.8 m/s at an angle of 553" above the horizontal. The rock hits the ground 5.72 s after it was kicked. How high is the cliff? (12b) What is the speed of the rock right before it hits the ground? (120) What is the maximum height of the rock in the air, measured from the top of the cliff