Answer:
The answer is 0.83 seconds.
Explanation:
The formula of free fall is following:

Where g=9.8 m/s^2 and t=2 seconds, the rock takes:

19.6 meters. This is the half distance of the cliff. The whole distance is 39.2 meters. So it takes:

2.83 second to fall down completely. The rock takes the second half of the cliff in 0.83 seconds
Answer:
A
Explanation: A is a example of Air resistance force, which is a contact force.
Answer:
Explanation:
28 / 70 = 0.3857142... = 0.39 hr
280 / 100 = 2.8 hrs.
(100 - 0) / 10 = 10 m/s²
(60 - 20) / 4 = 10 m/s²
this process is called parellelogram method of resolving vectors.
Explanation:
A student solving for the acceleration of an object has applied appropriate physics principles and obtained the expression :

Where


m = 7 kg
So, the correct step for obtaining a common denominator for the two fractions in the expression in solving for a is (a) and the value of a is :


Hence, the correct option is (a).