Recent content by dorothy

oh, so I should assume the volume is fixed if the question doesn’t mention about it. Is that right? May I also ask about (1) & (3) as well? thanks

(1) Incorrect, since the root mean square speed(c^2）is directly proportional to the temperature, but it will just affect the average kinetic energy, doubling the k.e., but not related to the potential energy. (2) Correct, since the volume of gas is directly proportional to the temperature (3)...

since the area of A from t=0s to t=5s and the area of B from t=0s to t=5s are different.

coz their displacement are not equal

I would like to ask Q19 as well. Thanks. (2) is correct because A&B have the same total displacement and they finish it with the same time 10s so the two objects have the same avg. velocity. (3) is correct because at t＝1s, the slope of A is greater than the slope of B, which means A has a...

I’m sorry. May I know whether my ans is correct or not? I think (1) & (3) are wrong because velocity and acceleration get direction(vectors) while speed doesn’t(scalar). Thank you.

i see , thanks

Besides Q3, do I get all correct in Q1-Q30? thanks

for Q3, it should be ''avg. velocity: [(5)(-20)÷2 +(2+7)(20)÷2]÷12 ＝ 3.3 m/s'', right?

I think so coz I found the avg. velocity to be 11.7 . Except Q3, do I get the questions(question1-30) all correct? thanks

The attached pdf is my solution. Thank you!

oh because I think that T is pointing upward so it won’t pass B. But for R, it is pointing horizontally and will pass B so its torque is 0.

because the force T is pointing upward and it doesn’t “push” the plank?

1. Yes, clockwise 2. Yes, anti-clockwise 3. No Ohhh is it because we need the moment due to f to balance with the moment due to W in order to reach the equilibrium?