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astarmathsandphysics:
http://www.astarmathsandphysics.com/a_level_maths_notes/M1/a_level_maths_notes_m1_impulse.html

You do need the speed of one of the particles after the collision, or a condition - the become one particle so have the same speed, one has twice the speed of the other, one particle comes to rest etc so you can use the formula Impulse=m(v-u)

ruby92:
A 30 kg block (M1) is placed on a frictionless plane that inclines at a 30° angle with respect to the surface of Earth. This block is connected to another 20 kg block (M2) via a weightless rope over a frictionless, ideal pulley. The second block is hanging vertically.
What is the tension of the rope?

(a) 55.0 N
(b) 92.4 N
(c) 147.4 N
(d) 176.6 N
(e) 294.6 N

explained as simple as possible  :(

ruby92:
A 10-kg sign is suspended by three ropes, each supporting an equal portion of the sign's weight. The two end ropes make an angle of 70º to the horizontal. What is the tension on each of the ropes?

could someone please solve this fast :( :(

A.T:

--- Quote from: ruby92 on March 25, 2010, 05:36:38 pm ---A 30 kg block (M1) is placed on a frictionless plane that inclines at a 30° angle with respect to the surface of Earth. This block is connected to another 20 kg block (M2) via a weightless rope over a frictionless, ideal pulley. The second block is hanging vertically.
What is the tension of the rope?

(a) 55.0 N
(b) 92.4 N
(c) 147.4 N
(d) 176.6 N
(e) 294.6 N

explained as simple as possible  :(

--- End quote ---

Resolving forces on the 30 kg mass:
T-30gsin(30)=ma
T-30gsin(30)=30a ....1

Resolving forces on 20 kg mass:
W-T=ma
20g-T=20a.....2

solving 1 and 2 simulataneously:
T-30gsin(30) + 20g-T = 30a + 20a
a=0.981 ms-2

T=20g-20a from 2
T=20*9.81 - 21(.981)
T=175.599=175.6 N

Hence answer is C




--- Quote from: ruby92 on March 25, 2010, 08:49:36 pm ---A 10-kg sign is suspended by three ropes, each supporting an equal portion of the sign's weight. The two end ropes make an angle of 70º to the horizontal. What is the tension on each of the ropes?

could someone please solve this fast :( :(

--- End quote ---

According to question it seems the center rope in vertical.
IF all ropes were vertical the tension in each string would be:
3T=W
3T=10g
T=100/3 N

Hence the center rope has a tension of 100/3 N

now for the end ropes, as they are at 70 degree angle both their vertical component is:
Tsin(70)=100/3
T=35.5N
hence tension in the both end rope is 35.5N

ruby92:
c are u sure?
isnt it d??

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