# Search results

1. ### Sound Intensity of a Whisper

Homework Statement What is the sound intensity of a whisper at a distance of 3.0 m, in W/m^2 ? What is the corresponding sound intensity level in dB? Homework Equations I=P/4*pi*r^2 The Attempt at a Solution I tried looking up what the power of a whisper was and I can't find...
2. ### Unit conversion difficulties on simple problem

Homework Statement A 55 g particle is moving to the left at 27 m/s. How much work must be done on the particle to cause it to move to the right at 41 m/s? Answer in joules Homework Equations The Attempt at a Solution 27-(-41)=68 , 68*55= 3750 the units here are grams m/s. I...
3. ### Work, displacement, and gravity problem!

Homework Statement A 1.4 kg book is lying on a 0.80 m-high table. You pick it up and place it on a bookshelf 2.2 m above the floor. 1) How much work does your hand do on the book? 2.) How much work does gravity do on the book? [solved] Homework Equations Force*displacement=work...
4. ### Friction and a skier

Homework Statement You are a member of an alpine rescue team and must get a box of supplies, with mass 2.20 kg, up an incline of constant slope angle 30.0 degrees so that it reaches a stranded skier who is a vertical distance 2.80 m above the bottom of the incline. There is some friction...
5. ### Locomotive, friction, and speed question

Homework Statement A 4.6×104 kg locomotive, with steel wheels, is traveling at 14 m/s on steel rails when its engine and brakes both fail. The coefficient of friction is 1.6×10−3. 1.) How far will the locomotive roll before it comes to a stop? Answer in meters using two significant...
6. ### Quick question about forces

Quick question about forces!!! Homework Statement A skier is sliding down a 15 degree slope. Friction is not negligible. Identify all forces on the skier. Homework Equations n/a The Attempt at a Solution The choices are: Tension, Kinetic Friction, Weight, Static Friction...
7. ### Forces on blocks with 3 different masses.

Homework Statement Blocks with masses of 4.0 kg, 8.0 kg, and 9.0 kg are lined up in a row on a frictionless table. All three are pushed forward by a 15 N force applied to the 4.0 kg block. 1.) How much force does the 8.0 kg block exert on the 9.0 kg block? 2.)How much force does the...
8. ### Tension in Cables

Homework Statement A 20 kg loudspeaker is suspended 2.5 m below the ceiling by two cables that are each 20 degrees from vertical. What is the tension the cables? Homework Equations The Attempt at a Solution I have no idea on what equation to use, considering we haven't even...
9. ### Position vector and magnitude problem

Homework Statement A position vector in the first quadrant has an x-component of 6.0m and a magnitude of 10m What is the value of its y-component? Homework Equations ? The Attempt at a Solution Well I originally thought I could draw a graph where x=6 and y=...then I realized i...
10. ### Deceleration and reaction time physics problem

Homework Statement You're driving down the highway late one night at 16 m/s when a deer steps onto the road 39 m in front of you. Your reaction time before stepping on the brakes is 0.50 s, and the maximum deceleration of your car is 12 m/s^2 . How much distance is between you and the...
11. ### Rock tossed straight up-Velocity question

Homework Statement A rock is tossed straight up with a speed of 21 m/s. When it returns, it falls into a hole 15 m deep. What is the rock's velocity as it hits the bottom of the hole? How long is the rock in the air, from the instant it is released until it hits the bottom of the hole...