Physics: Post your doubts here!

[bamteck]

Here u r.....
i've made it simpler as possible if still u can't then i can't do otherwise

Thank you very much mate ! Now, I got it.

 

[Varuna0911]

U must have done these type of quest in mechanics.. u r frm mru i fink??

well
its simple simultaneous enqs

Using newton(my friend) laws of motion
2g - T = 2a eqn 1

T - 6 = 8a eqn 2


U solve simultaneously u'll get a = 1.4 ms^-2

T =17.2 N

hence a=1.4 ans is option A

thanks a lot..yess I am

 

[yumichikabyakuya renji]

hey
someone has the mark scheme of nov 02 p1??

 

[asangietalks]

can someone help do question 6c? http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_qp_22.pdf
thanks.

 

[Haseefa]

How do I do this?

When a golfer hits a ball, his club in in contact with the ball for about 0.0005s and the ball leaves the club with a speed of 70m/s. The mass of the ball is 46g.

a) Determine the mean accelerating force.
b) What mass, resting on the ball would exert the same force as in a?

 

[FeLiX zoe]

Does anyone have any simple notes on Atomic Physics ???

 

[nightrider1993]

can someone help do question 6c? http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_qp_22.pdf
thanks.

I hope this anwsers ur question

 

[nightrider1993]

How do I do this?

When a golfer hits a ball, his club in in contact with the ball for about 0.0005s and the ball leaves the club with a speed of 70m/s. The mass of the ball is 46g.

a) Determine the mean accelerating force.
b) What mass, resting on the ball would exert the same force as in a?

Answers
a) Impulse = (force)(change in time) = momentum
therefore,
Force= (0.046*70)/(0.0005) = 6440N

b) i dont understand the question

 

[nightrider1993]

hey
someone has the mark scheme of nov 02 p1??

The answers for MCQ are in this examiner report

 

[nightrider1993]

Answers
a) Impulse = (force)(change in time) = momentum
therefore,
Force= (0.046*70)/(0.0005) = 6440N

b) i dont understand the question

Do you know the answer to part b?

 

[nightrider1993]

How do I do this?

When a golfer hits a ball, his club in in contact with the ball for about 0.0005s and the ball leaves the club with a speed of 70m/s. The mass of the ball is 46g.

a) Determine the mean accelerating force.
b) What mass, resting on the ball would exert the same force as in a?

Do you know the answer to part b?

 

[Haseefa]

Do you know the answer to part b?

a)(70-0)/0.0005 = 140,000

F=ma
= 0.046 x 140,000
= 6440 N


b) F=ma
6440= mx 9.81
m = 656.47 kg

answer provided by badrobot14

 

[asangietalks]

I hope this anwsers ur question

thank you so muchh,,,, now i get it.. thankss....

 

[Haseefa]

When jumping from a wall onto the ground, it is advisable to bend one's knees on landing. Using Newton's second law of motion, explain why it is sensible to bend one's knees..?

smzimran Could you help me here?

 

[smzimran]

When jumping from a wall onto the ground, it is advisable to bend one's knees on landing. Using Newton's second law of motion, explain why it is sensible to bend one's knees..?

smzimran Could you help me here?

If you jump off a table, as your feet hit the floor, you let your legs bend at the knees in order to mimimize the force applied to your skeletal system.
Just before you reach the floor your body has momentum.
After you land, your body will have no momentum, so therefore there was a change in momentum and an impulse was necessary for this to happen.

The impulse on your body in this case comes from the floor and the size of the impulse is constant. Since impulse is the product of the force and the time over which it acts, then force and time are inversely proportional. So, if the force acts over a longer time period, then it will have a smaller magnitude. If we didn't bend our knees, the force would act over a much shorter period of time and would thus be much greater in magnitude, great enough to break our bones.

 

[nightrider1993]

a)(70-0)/0.0005 = 140,000

F=ma
= 0.046 x 140,000
= 6440 N


b) F=ma
6440= mx 9.81
m = 656.47 kg

answer provided by badrobot14

lol, that simple,eh...

 

[elbeyon]

Can anyone help me out for this question:
The answer is B.

 

[nightrider1993]

Can anyone help me out for this question:
The answer is B.

Remember that the voltage in parallel is same.

For top part:
The voltage across 500 resistor (PX) is 4 volts:
Voltage across PX= (500/1500)*12 = 4 V

For bottom part:
The voltage across 2000 resistor (PY) is 8 volts:
Voltage across PY= (2000/3000)*12 = 8V

Therefore, voltage across XY= 8-4 = 4 V

 

[nightrider1993]

When jumping from a wall onto the ground, it is advisable to bend one's knees on landing. Using Newton's second law of motion, explain why it is sensible to bend one's knees..?

smzimran Could you help me here?

The Force break up into different components, ie, horizontal and vertical components. Therefore less force is applied on the tibia and femur (skeletal bones)

 

[elbeyon]

Remember that the voltage in parallel is same.

For top part:
The voltage across 500 resistor (PX) is 4 volts:
Voltage across PX= (500/1500)*12 = 4 V

For bottom part:
The voltage across 2000 resistor (PY) is 8 volts:
Voltage across PY= (2000/3000)*12 = 8V

Therefore, voltage across XY= 8-4 = 4 V

Thanks a lot dude !