The statement that motion is relative is an important concept in physics. The meaning behind this statement is that the motion of an object is relative to either the frame of reference of the observer, or to another distinct frame of reference.
Answer: 3.4s
Explanation:
There are three stages in the motion of the ball, so you have to calculate the times for every stage.
1) Ball dropping from 9.5m: free fall
d = Vo + gt² / 2
Vo = 0 ⇒ d = gt² / 2 ⇒ t² = 2d / g = 2 × 9.5 m / 9.81 m/s² = 1.94 s²
⇒ t = √ (1.94 s²) = 1.39s
2) Ball rising 5.7m (vertical rise)
i) Determine the initial speed:
Vf² = Vo² - 2gd
Vf² = 0 ⇒ Vo² = 2gd = 2 × 9.81 m/s² × 5.7m = 111.8 m²/s²
⇒ Vo = 10.6 m/s
ii) time rising
Vf = Vo - gt
Vf = 0 ⇒ Vo = gt ⇒
t = Vo / g = 10.6 m/s / 9.81 m/s² = 1.08 s
3) Ball dropping from 5.7 m to 1.20m above the pavement (free fall)
i) d = 5.7m - 1.20m = 4.5m
ii) d = gt² / 2 ⇒ t² = 2d / g = 2 × 4.5 m / 9.81 m/s² = 0.92 s²
⇒ t = √ (0.92 s²) = 0.96s
4) Total time
t = 1.39s + 1.08s + 0.96s = 3.43s ≈ 3.4s
Answer:
c is correct
Explanation:
Steel is a metal that is made from iron and carbon. During the steel making process, iron & carbon are melted together, and is allowed to harden into a solid. The iron and the carbon DO NOT chemically react with each other. After the steel was made, 20 samples were taken from one piece and tested. Each sample contained 98% iron and 2% carbon.
Which of the following terms BEST describes steel? homogeneous mixture
(physics: really?)
It's 0.125 cm or 1.25 mm. Divide 1cm (or 10mm) by 8.
Answer:
Explanation:
We use the following rotational kinematic equation to calculate the angular acceleration of the rod:
Here 
is the final angular speed, 
is the initial angular speed and 
is the angular acceleration. The rod starts rotating from rest (
):
Recall that the angular speed is defined in function of the tangential speed (v) and the radius (r) of the circular motion:
In this case the radius is given by 
. Replacing (2) in (1):
