# Search results

1. ### Trying to find the amount of stretch of a spring for a launch

Homework Statement I'm doing an experiment where I have to calculate the stretch of a spring needed for it to launch itself into a trashcan located some distance away. The spring is located on the edge of a ramp that is 1.13 m high. The angle of the ramp is 30 degrees above horizontal. The...
2. ### Galilean transformation problem (Speed)

Why wouldn't it be +126 m if she is moving forward?
3. ### Galilean transformation problem (Speed)

Homework Statement A girl is riding a bicycle along a straight road at constant speed, and passes a friend standing at a bus stop (event #1). At a time of 60 s later the friend catches a bus (event #2) If the distance separating the events is 126 m in the frame of the girl on the bicycle...
4. ### A pulley system with two objects stacked on each other

no when you add the 3 equations together you only have 2 unknowns. Then if you find the acceleration (7.35) and solve for mC you get 39 kg, which seems to be the correct answer.
5. ### A pulley system with two objects stacked on each other

Homework Statement Block B, with mass 5.00kg, rests on block A, with mass 8.00kg , which in turn is on a horizontal tabletop. There is no friction between block A and the tabletop, but the coefficient of static friction between block A and block B is 0.750. A light string attached to block A...
6. ### Finding the time when two stones cross paths

##D_A + 6.69 = D_B## It took me a while, but I finally found meaning behind this equation... displacement of rock A: ##D_A = -6.69 m [up]##, and B: ##D_B = 0 m.## -6.69 + 6.69 = 0, brilliant!
7. ### Finding the time when two stones cross paths

Homework Statement Two stones are thrown simultaneously, one straight upward from the base of a cliff and the other straight downward from the top of the cliff. The height of the cliff is 6.69 m. The stones are thrown with the same speed of 9.97 m/s. After what time do the stones cross paths...
8. ### Average Speed vs. Instantaneous Speed

you are right
9. ### How do you do analysis of units?

Homework Statement Show the unit analysis of this equation that relates frequency to length (in centimeters) of a pendulum f = 5.1L^{-0.5} Homework Equations f = \frac{1}{2\pi\sqrt{\frac{L}{g}}} ? The Attempt at a Solution I cannot find much info about this online, but I gave it a go: f...
10. ### Relationship between frequency and length of pendulum

Homework Statement We calculated times of the periods of varying pendulum lengths. (20cm, 40cm, 60cm, 80cm). Then the frequency was calculated for each length and then a frequency-length graph was made. Since the graph is an exponential relationship we graphed our values on a log-log chart...
11. ### Height when a ball is thrown vertically at half its velocity

I didn't fully understand what you mean
12. ### Height when a ball is thrown vertically at half its velocity

Homework Statement A baseball is thrown vertically into the air with a velocity, v, and reaches a maximum height, h. At what height was the baseball with one-half its original velocity? Assume no air resistance. Homework Equations v22 = v12 + 2ad ? The Attempt at a Solution let...
13. ### Mass of block given μK and Force?

Fnet = 240 - (0.4 x 9.8m) = 240 - 3.92m 240 - 3.92m = 0.88m 240 = 0.88m + 3.92m 240 = 4.8m m = 50 kg wohooooooo thanks a lot!:biggrin:
14. ### Mass of block given μK and Force?

240 - 2.92m = 0.88m 240 = 0.88m + 2.92m 240 = 3.8m m = 63 kg
15. ### Mass of block given μK and Force?

oh wow my bad... Fnet = 240 - (0.4 x 9.8m) = 240 - 2.92m Still don't get what I need to do next?
16. ### Mass of block given μK and Force?

Fapplied = 0.88m just guessing here: Fnet = FA [fwd] + Ff [bwd] Fnet = FA [fwd] - Ff [fwd] Fnet = 0.88m - (0.4 x 9.8m)
17. ### Mass of block given μK and Force?

μK = FK / FN FK = μK × FN FK= 0.4 x 9.8m I have 2 unknowns?
18. ### Mass of block given μK and Force?

weight = 9.8m
19. ### Mass of block given μK and Force?

force applied of 240 N and kinetic friction I can't find magnitude of kinetic friction because I cannot find Force normal.
20. ### Mass of block given μK and Force?

μK = FK / FN FN = FK / μK mg = FK / μK m = (FK / μK) / g Like this?
21. ### Mass of block given μK and Force?

Homework Statement A student pushes a block with 240 N of force across a horizontal surface with a coefficient of kinetic friction of 0.4. The block accelerates at a rate of 0.88 m/s2. Find the mass of the block. Homework Equations μK = FK / FN F=ma The Attempt at a Solution...
22. ### Final velocity of this hockey puck

I feel dumb, thanks.
23. ### Final velocity of this hockey puck

Homework Statement In the last second of a hockey game, a player slaps the puck in the empty net 32.5 m away. The puck leaves the stick with the speed of 41.5 m/s. Calculate the final velocity of the puck if its mass is 0.17 kg. Homework Equations μK = 0.005 μK = FK / FN F = ma v22 = v12...
24. ### Finding mass of this car

Wait, is the normal force simply the force of all the wheels ?
25. ### Finding mass of this car

Homework Statement Each of the four wheels of a car pushes on the road with a force of 4.0 x 103 N [down]. The driving force on the car is 8.0 x 103 N [west]. The frictional resistance on the car is 6.0 x 103 N [east]. Calculate the mass of the car. Homework Equations F = ma Fnet = F1 +...
26. ### Frictional Forces

Sorry, do you have mass?
27. ### Frictional Forces

Are you given mass of the baseball player?
28. ### Does force normal change when you push an object at an angle?

Thanks, but I have a question. Why doesn't the force of gravity on the lawn mower increase when you apply your force on it? Aren't you essentially making the lawn mower heavier?
29. ### Does force normal change when you push an object at an angle?

Homework Statement You exert a force of 131 N [30° below horizontal] onto a 12.6 kg lawn mower, What is the force of gravity and normal force on the lawn mower? Homework Equations Fg= m × g FA (y component) = Sin30° × FA The Attempt at a Solution The force of gravity is equal to the force...
30. ### Force required to pull trunk across floor

Homework Statement You are dragging a 110 kg trunk across a floor at a constant velocity with horizontal force of 380 N. A friend decides to help by pulling on the trunk with a force of 150 N [up]. Will this help? Calculate the force required to pull the trunk at a constant velocity to help...