# Search results

1. ### Solve log(x) + log(x+3) = 1

I know this is an old post but incase people find it in the future: rule 1) logbx + logby = logbxy rule 2) x (x + a) = x2 + ax rule 3) solving quadratic equations

3. ### Projectile Motion bombarding cancer tumors

maybe you could try working backwards to see what you've done wrong. i think that you've used some values in the wrong places
4. ### Forces - Elevator 2 part question

Do you have any formulae at all? Do you understand the concept of what is happening when the elevator is moving?
5. ### Young's modulus of spider thread

Yeah, i was taking the radius as the radius of the web. so i've done this: nb: s=spider p=person a) What is the fractional increase in the thread’s length caused by the spider? Y_s = 4.7x10^9 N/m^2 m = 0.26g = 2.6x10^-^4 kg r_s = 9.8x10^-^6 m F = Y(\frac{A_o}{L_o})\Delta L => mg =...
6. ### Young's modulus of spider thread

Homework Statement Q 1. A spider with a mass of 0.26 g hangs vertically by one of its threads. The thread has a Young’s modulus of 4.7 x 10^9 N/m2 and a radius of 9.8 x 10^- ^6 m. a) What is the fractional increase in the thread’s length caused by the spider? b) Suppose a 76 kg person...
7. ### I lost my calculaor Plz calculate this for me

if you have a pc go through the start menu -> programs -> accessories -> calculator select view -> scientific for more options if you have a mac there should just be a pic of a calculator on the desktop
8. ### Rotational motion

thanks i didn't realised i'd overlooked that information so: a) \omega = \frac{v}{r} = \frac{28.8}{2} = \underline{14.4rad/s} b) f_cp = ma_cp = \frac{mv^{2}}{r} = mr\omega^{2} = 7.26 x 2 x 14.4^{2} =3010.8672 = \underline{3.01 x 10^{3}N} c) F=mg F=f_cp = 3011N, g=9.81m/s^{2}...
9. ### Rotational motion

On his last throw of the Atlanta Olympics, Lance Deal launched the hammer 81.12m, good enough for a silver medal. The hammer is thrown by rotating the body in a circle, building up rotational speed until releasing it and letting the rotational velocity change to translational velocity. The...
10. ### Rotational motion of bicep

so if i change sin 20 to cos 20 (or sin 110) i get: \tau1 = Fsin = mgsin = 1.1 x -9.81 x cos 20 x 0.15 = -1.521Nm \tau2 = Fsin = mgsin = 20 x -9.81 x cos 20 x 0.3 = -55.310Nm -3 = 1 + 2 = -1.521 + -55.310 = -56.831Nm therefore 3 = 56.831Nm or 56.831Nm in an anticlockwise...
11. ### Rotational motion of bicep

ok so \tau1 = Fsin\theta = mgsin\theta = 1.1 x -9.81 x sin 20 x 0.15 = -0.5536Nm \tau2 = Fsin\theta = mgsin\theta = 20 x -9.81 x sin 20 x 0.3 = -20.131Nm -\tau3 = \tau1 + \tau2 = -0.5536 + -20.131 = -20.685Nm therefore \tau3 = 20.685Nm or 20.685Nm in an anticlockwise direction
12. ### Rotational motion of bicep

sorry i forgot about the 3rd force \Sigma\tau = 0 \tau1 + \tau2 + \tau3 = 0 \tau1 + \tau2 = -\tau3 but i'm a little unsure about the force of \tau2 (which i have as the object) is it: -\tau3 = \tau1 + \tau2 = m1gx1 + m2gx2 = 1.1 x 9.81 x 0.15 + 20 x 9.81 0.3 = 60.47865N \tau3 =...
13. ### Physics Homework need help for answers/also explain how to do them

2) a) plot a graph on a piece of paper with speed/velocity on the side and time on the bottom (i'd just put 1hr, 2hr, 3hr etc for each of the velocities [unless you got given something]) b) those 3 equations that you have are just different ways of writing the same thing. anyhow you have two...
14. ### Rotational motion of bicep

would someone be able to tell me if this is right or what i've done wrong? thankyou Homework Statement a) What torque does the bicep muscle have to apply to hold the forearm of mass 1.10 kg and length 30 cm horizontally? Assume the arm is a rod of uniform mass density. b) What torque does...
15. ### Electricity prob

part 2 retry - electricity P = VI = \frac{V^{2}}{R} = I^{2} I_{1+2} = 0.6A R = 7+5 = 12\Omega P = 0.6^{2} x 12 = 4.32W V^{2} = PR = 4.32 x 12 = 51.84V V = 7.2V P = I^{2} x 16 = 4.32 I^{2} = \frac{4.32}{16} = 0.2A I = 0.5A I = \frac{\epsilon}{R} \epsilon = IR = 0.5 x 12 = 6V
16. ### Electricity prob

The values for the resistors are: R1=7\Omega, R2=5\Omega, R3=4\Omega (see diagram for placement of the resistors) 1) Suppose there is a current of 0.6A going through R1 and that the voltage supplied by the battery is 9V, determine the value of R4 2) Using the information above, determine the...
17. ### Pressure of fluid on bottom of container

new pressure ok so v = 2.05 x 10^{-3} m^{3} CSA = 65.2 cm2 = 6.52 x 10^{-3} m^{3} h = \frac{v}{CSA} =0.3144m P = \rhogh = 806 x 9.81 x (14.67 + 0.314) = 806 x 9.81 x 14.985 = 118 486.05 Pa = 1.18 x 10^{5} Pa = 118 kPa thankyou
18. ### Pressure of fluid in container

sorry i didn't mean to finish it yet there is a later post with more in it
19. ### Pressure of fluid on bottom of container

A cylindrical container with a cross sectional area of 65.2 cm^{2} holds a fluid of density 806kg/m^{3}. At the bottom of the container the pressure is 116 kPa a) What is the depth of the fluid? b) Find the pressure at the bottom of the container after an additional 2.05 \times 10^{-3} m^{3}...
20. ### Pressure of fluid in container

Homework Statement A cylindrical container with a cross sectional area of 65.2 cm^{2} holds a fluid of density 806kg/m^{3}. At the bottom of the container the pressure is 116 kPa a) What is the depth of the fluid? b) Find the pressure at the bottom of the container after an additional 2.05...
21. ### Another motion prob

thanks learningphysics cool so it's: vy^{2} = voy^{2} - 2g\Deltay 0^{2} = voy^{2} - 2\times9.81\times1.1 voy^{2} = 21.582 voy = 4.65 m/s vx = vox voy = 6.5 m/s vo = \sqrt{voy^{2} + vox^{2}} = \sqrt{4.65^{2} + 6.5^{2}} = \sqrt{21.582 + 42.25} = \sqrt{63.832} = 7.989 m/s...
22. ### Another motion prob

_{}Homework Statement If a long jumper at the top of his projectory is moving at 6.5 m/s (horizontally) and his cantre of mass is 1.1m above where it was when he launched into the jump, how fast must he have been moving when he launched? Homework Equations v_{x} = v_{0x} + a_{x}t x =...

24. ### Density prob

Homework Statement a person sits in a harness hamging in mid-air from a set of scales. the scales display her weight as 550.0 N. she then empties her lungs as much as possible and is completely immersed in water. the scales now give her weight as 21.2 N. what is her average density...
25. ### Motion equations problem

thanks for that, i didn't even consider energy and those formulae are included too so no memorising once again thanks a bunch
26. ### Motion equations problem

I have a problem from a practice physics exam: The specifications for design of a playgroud slide say that a child should gain a speed of no more than 15m/s by sliding down the eqipment. How tall can the slide be? these are the equations that we'll be given in our exam: v_{x} = v_{0x} +...