A. Cause and effect.
Explanation:
An experiment can prove cause and effect in a study unlike observational studies.
- Observational studies is a non-experimental system of investigation.
- It helps to identify the causes(independent variable) and the effect(dependent variables).
- In observational studies, the variables cannot be controlled and so it is difficult to prove the cause and effect.
- An experiment can prove cause and effect because the parameters are tested and can be controlled.
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Answer:
640 m.
Explanation:
The following data were obtained from the question:
Acceleration (a) = –20 m/s/s
Time (t) = 8 s
Final velocity (v) = 0 m/s
Distance (s) =.?
Next, we shall determine the initial velocity (u) of the car. This can be obtained as follow:
Acceleration (a) = –20 m/s/s
Time (t) = 8 s
Final velocity (v) = 0 m/s
Initial velocity (u)
a = (v – u) / t
–20 = (0 – u) / 8
–20 = – u / 8
Cross multiply
–20 × 8 = – u
– 160 = – u
Divide both side by – 1
u = – 160 / – 1
u = 160 m/s
Finally, we shall determine the distance travelled by the car before stopping as follow:
Time (t) = 8 s
Final velocity (v) = 0 m/s
Initial velocity (u) = 160 m/s
Distance (s) =.?
s = (v + u)t /2
s = (0 + 160) × 8 /2
s = (160 × 8) /2
s = 1280 / 2
s = 640 m
Therefore, the car travelled 640 m before stopping.
Answer:
The acceleration of the ball as it rises to the top of its arc equals 9.807 meters per square second.
Explanation:
Let suppose that maximum height of the arc is so small in comparison with the radius of the Earth.
Since the ball is launched upwards, then the ball experiments a free-fall motion, that is, an uniform accelerated motion in which the element is accelerated by gravity. Then, the acceleration experimented by the motion remains constant at every instant and position.
Besides, the gravitational acceleration in the Earth and, in consequence, the acceleration of the ball as it rises to the top of its arc equals 9.807 meters per square second.
