Diagram 7 shows the velocity-time graph of an object for 12 s.

When is the object at a distance of one-quarter of
the total distance travelled in the 12 s?
A 3 s
B 4 s
C 5 s
D 6 s

*The answer is D but can anyone tell me the solving steps? Or perhaps the answer is wrong?*

Acar travels 40m in 8 seconds find the car speed

Calculate a pendulums frequency of oscillation (in hz) if the pendulum completes one cycle in 0.5s.

Researchers conducted an experiment to identify the effects of three different hand sanitizers on the growth of bacteria. the researchers grew one type of bacteria in twenty-four identical covered petri dishes. then, they opened eighteen petri dishes and applied the three hand sanitizers to six petri dishes each. they left the remaining six petri dishes closed as a control group. when the researchers measured the growth of bacteria two days later, the six dishes that had no hand sanitizer showed the least amount of bacterial growth. the researchers concluded that not using any hand sanitizer would lead to the least bacterial growth. which statement best explains why the researchers’ conclusion was not justified? the experiment tested too many variables. the control group was not treated the same as the experimental group. the sample size of twenty-four petri dishes is not large enough. the single type of bacteria is not adequate to make any conclusions.