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Physics: Post your doubts here!

Snow Angel

Snow Angel

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usama321 said:
We know that the breaks were applied when the skid marks appeard. We also know the final speed would be zero. Use
2as = vsquare - u square
for second part he is asking the time interval before the brakes were applied

Just use s = ut + 1/2atsquare ( no acceleration)
Click to expand...
thnx

but how do u know that the skid marks appeared when the breaks were applied
 
usama321

usama321

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Snow Angel said:
thnx

but how do u know that the skid marks appeared when the breaks were applied
Click to expand...
The questions says "
With the brakes applied, the front
wheels of the car leave skid marks on the road that are 12.8 m long, as illustrated in Fig. 2.1"
 
Umer Jawed

Umer Jawed

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Assalamualaikum I have problem in J2011 P23 Q6b and c(iv). Please help me with the sketches. I would be glad!
 
Thought blocker

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A

amal sharkawi

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A strong wind of speed 33 m s–1 blows against a wall. The density of the air is 1.2 kg m–3. The wall
has an area of 12 m2
at right angles to the wind velocity. The air has its speed reduced to zero
when it hits the wall.

What is the approximate force exerted by the air on the wall?
A 330 N B 400 N C 480 N D 16 000 N

can someone explain me this
 
A

asma tareen

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amal sharkawi said:
A strong wind of speed 33 m s–1 blows against a wall. The density of the air is 1.2 kg m–3. The wall
has an area of 12 m2
at right angles to the wind velocity. The air has its speed reduced to zero
when it hits the wall.

What is the approximate force exerted by the air on the wall?
A 330 N B 400 N C 480 N D 16 000 N

can someone explain me this
Click to expand...
agha saad 22
 
usama321

usama321

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meerul264 said:
thanks but i'm still confused a bit. can you please explain to me the full concept of this question (about potential divider?) ?
Click to expand...
As CB also has resistance, just think of it as another resister in series with the two parallel resistors. now if the emf of the batter is 6v (dont remember the question), some of the voltage would be dissipated across the CB resistor first, and the rest of 6v is then equally dissipated across the two parallel resistors

e.pnganothe
 
usama321

usama321

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amal sharkawi said:
A strong wind of speed 33 m s–1 blows against a wall. The density of the air is 1.2 kg m–3. The wall
has an area of 12 m2
at right angles to the wind velocity. The air has its speed reduced to zero
when it hits the wall.

What is the approximate force exerted by the air on the wall?
A 330 N B 400 N C 480 N D 16 000 N

can someone explain me this
Click to expand...
Mass of wind coming in contact with the blades per second = density * speed * area = 475.2 kg/s

F = mv-mu/t As it is 475.2 kg/s, we will use
F = 475.2*0 - 475.2*33/1 = D
 
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