# Search results

1. ### Angular momentum

OK so if: L_{1}=I_{d}\omega_{1} and L_{2}=I_{d+p}\omega_{2}= I_{d}\omega_{2}+I_{p}\omega_{2} where \omega_{1} = 20rpm and \omega_{2} = 16rpm Then because angular momentum is conserved, L_{1}=L_{2} and I_{d}\omega_{2}+I_{p}\omega_{2}=I_{d}\omega_{1} Is it correct to treat the...
2. ### Angular momentum

Homework Statement The question involves a rotating disc, spinning about a vertical axis through its centre. We are given its angular speed, 20rpm and diameter 24cm. A piece of plasticine is dropped onto the disc (no torques are applied by this process). We are given its location relative...
3. ### Integration problem

Now I'm more confused... How can }du&=&-\frac{{\rm d}u}{k} ?
4. ### Integration problem

Homework Statement I was given that \int \frac{m}{mgsin\alpha-kv} dv = -\frac{m}{k}ln(mgsin\alpha-kv) + C ..but I can't 'see' how this was done. Homework Equations The Attempt at a Solution My first thought is that this is somehow related to the fact that: \int...
5. ### Energy stored in springs

I managed to make this way more complicated for myself than it needed to be... thanks for the help. i had been trying to come up with a single equation but with two unknown extensions i was getting myslef in a quite a muddle. SOLVED. thanks.
6. ### Energy stored in springs

Homework Statement A particle (4m) is suspended from a fixed point by a spring of stiffness k and natural length l0. An identical 2nd spring is attached to this particle, and a mass (3m) is attached to its end. The system hangs vertically in equilibrium. Take the datuim of P.E. a in each...
7. ### Collision problem

Perfect! Thanks
8. ### Collision problem

Homework Statement Three particles, A,B,C all of equal mass m,collide at the origin. Prior to the collsion the particles are moving as follows: A has speed u in direction (1/sqrt(2))(-i-j) B has speed v in direction (sqrt(3)/2)i+(1/2)j C has speed w in direction -i After the collision all...
9. ### Find position vector from given velocity

Well that makes sense thanks... back to the books now Thanks again for the help CFDFEAGURU and RoyalCat
10. ### Find position vector from given velocity

I'm trying to follow.. So r(0)=0 Therefore r(t)=vt + C must give C=0 so r(t)=vt = 7ti-4tj ?
11. ### Find position vector from given velocity

Homework Statement A particle A of mass m is travelling on a horizontal surface with velocity 7i-4j and collides with a stationary particle of mass 3m at the origin of the co-ordinate system at time t=0 Find an expression for the position vector of A at time t<0 NB: There is more to...