Answer:
This question lacks options, the options are:
A. the number of days the rainwater was allowed to sit
B. the number of times the rainwater was observed
C. the change in the amount of rainwater due to evaporation
D. the change in pH of the rainwater over time
The answer is A
Explanation:
In an experiment, the independent variable is the variable that is changed or manipulated by the experimenter in order to effect a measurable response.
In this experiment, Austin is trying to determine how time changes the pH of standing rainwater. He collects rainwater and distributes it evenly in 5 jars, which he measured the pH at different days using a pH testing kit. Hence, the independent or manipulated variable is THE NUMBER OF DAYS THE RAINWATER WAS ALLOWED TO SIT before measuring their pH.
Answer: Scientists used relative dating and absolute dating.
Explanation:
Scientists used absolute dating to determine the actual number of years ago that events happened. They used relative dating to divide Earth's past into several time frames when similar organisms were on Earth.
True! In order for work to be done, a force must cause movement.
Answer:
FALSE
Explanation:
Temperature inversion usually refers to the situation where a warm air lies over a cooler air that is present from the surface of the earth up to a certain height.
Normally, the temperature increases with increasing height. But, in the case of temperature inversion, the reverse of it takes place. This layer of inversion may occur at any place within the level of the troposphere.
This temperature inversion obstructs the atmospheric flow due to which the air mass present over a particular area become stable, resulting in a number of weather patterns.
On the other hand, greenhouse gases are those gases that can hold the incoming solar energy and radiate back into the atmosphere, thereby resulting in an increase in temperature of the atmosphere. Example, CO₂, CFC, H₂O and CH₄.
Hence, the above-given statement is false.
Answer:
F = 1094.4 N
Explanation:
From impulse - momentum theorem, we now that ;
Impulse = momentum
Where;
Formula for impulse = force (F) × time(t)
Momentum = mass(m) × velocity(v)
Now, we are given;
Mass of swimmer; m = 72 kg
Speed; v = 3.8 m/s
Time; t = 0.25 s
Thus;
F × t = mv
F = mv/t
F = (72 × 3.8)/0.25
F = 1094.4 N
This value of force is the magnitude of the average horizontal force by diver on the raft.
