physics question.....

[hassam]

 

[Zishi]

According to me the answer should be B which is 1.7 m/s^2.

The thing is that the weight of the 2kg mass acts as Tension in the string which pulls the box.

So Tension minus frictional force = ma
(2x9.81)-(6)=8xa
a=1.7

Hope it helps. I don't know whether my answer is right ot wrong.

 

[larina]

force= mass x acceleration
acc. = force/ mass

the force is----> W=mg
=2.0 x 9.81 = 19.62 N
therefore the resultant force is----> 19.62 - 6 (fritional force) = 13.62 N

the total mass is---->the acc. of the box is caused by the 2kg block plus the mass itself..so the total mass is 2+8=10 kg

acc. = force/ mass
10.62/ 10 = 1.362 = 1.4 m/s2 so its (A).

 

[Zishi]

force= mass x acceleration
acc. = force/ mass

the force is----> W=mg
=2.0 x 9.81 = 19.62 N
therefore the resultant force is----> 19.62 - 6 (fritional force) = 13.62 N

the total mass is---->the acc. of the box is caused by the 2kg block plus the mass itself..so the total mass is 2+8=10 kg

acc. = force/ mass
10.62/ 10 = 1.362 = 1.4 m/s2 so its (A).

Why did you add the mass of that 2kg in f=ma while calculating the acceleration? Won't we take only 8kg, cuz we're calculating ITS acceleration... =s

 

[hassam]

ya zishi i was also thinking the same but larina is ryt cos markscheme says ans is A

 

[hassam]

the total mass is---->the acc. of the box is caused by the 2kg block plus the mass itself..so the total mass is 2+8=10 kg
plzx elaborate this point larina

 

[hassam]

hhmmm.....i got it ...

 

[larina]

my teacher told me that we take the total mass because the accerleration of the 8kg block is caused by the 2kg block...and the 2 blocks are moving together...so for calculating the accerleration of the 8kg block we add both masses together.

 

[bibeksharma]

why 20-T=2a and what is T that is acting up in the mass 2 kg as you have stated T as the resultant force in mass 8 kg?

 

[bibeksharma]

Mass won't be added in above solution because tension T is created by mass 2 Kg on string.

 

[hassam]

well i thought it was so abvious that i do not need to mention bt anywayx T is the tension in string which is a bi-directional force