Wednesday

July 30, 2014

July 30, 2014

Total # Posts: 24

**Physics Help**

1.9 kg block slides along a frictionless surface at 1.8 m/s. A second block, sliding at a faster 4.5 m/s, collides with the first from behind and sticks to it. The final velocity of the combined blocks is 3.5 m/s. What was the mass of the second block? How do you set this equa...

**Need this soon!!**

I'm on my last try and I dont know how to do it!

**Thank you!**

That really helped thank you very much

**Physics**

A 40 g marble moving at 2.3 m/s strikes a 29 g marble at rest. Assume the collision is perfectly elastic and the marbles collide head-on. What is the speed of the first marble immediately after the collision? What is the speed of the second marble immediately after the collisi...

**Physics **

Never mind I got it!

**Physics **

Marissa drags a 15 kg duffel bag 18 m across the gym floor. If the coefficient of kinetic friction between the floor and bag is 0.15, how much thermal energy does Marissa create? It says I'm look for deltaE_Th. I dont know what that means or how to figure out the problem.

**Physics **

A car is traveling at 14 m/s. How fast would the car need to go to double its kinetic energy? By what factor does the car's kinetic energy increase if its speed is doubled to 28 m/s? We only get 3 chances and I'm on my last one before I get the question wrong, help?

**Physics help**

Awesome thanks a lot!

**Physics help**

A 300 g bird flying along at 6.4 m/s sees a 10 g insect heading straight toward it with a speed of 34 m/s (as measured by an observer on the ground, not by the bird). The bird opens its mouth wide and enjoys a nice lunch. What is the bird's speed immediately after swallowi...

**Physics**

A 1.1 kg book is lying on a 0.77 m -high table. You pick it up and place it on a bookshelf 2.3 m above the floor. 1. How much work does gravity do on the book? 2. How much work does your hand do on the book? How do you find work?

**Physics**

A man standing on very slick ice fires a rifle horizontally. The mass of the man together with the rifle is 70 kg, and the mass of the bullet is 10g. Q:If the bullet leaves the muzzle at a speed of 500 m/s, what is the final speed of the man? I dont know how to set this up, help?

**Physics**

I'm not sure how to solve for k though.

**Physics**

A compact car has a mass of 1400kg. Assume that the car has one spring on each wheel, that the springs are identical, and that the mass is equally distributed over the four springs. What is the spring constant of each spring if the empty car bounces up and down 1.9 times each ...

**physics**

A 3.0-m-long rigid beam with a mass 130 kg is supported at each end. An 90 kg student stands 2.0 m from support 1. (beam 1 is to the left, and beam 2 is on the right.) How much upward force does support 1 exert on the beam? How much upward force does support 2 exert on the beam?

**physics**

A spring exerts a 17 N force after being stretched by 3.0 cm from its equilibrium length. By how much will the spring force increase if the spring is stretched from 5.0 cm away from equilibrium to 6.0 rm cm from equilibrium? I dont know how to approach this at all or how to so...

**Physics**

Flywheels are large, massive wheels used to store energy. They can be spun up slowly, then the wheel's energy can be released quickly to accomplish a task that demands high power. An industrial flywheel has a 1.5 m diameter and a mass of 250 kg. Its maximum angular velocit...

**Physics**

The centers of a 15 kg lead ball and a 140 g lead ball are separated by 8.0 cm. What gravitational force does each exert on the other? Answer: 2.2×10^−8 N Now: What is the ratio of this gravitational force to the weight of the 140 g ball? I dont know how to do this...

**Physics**

An object's moment of inertia is 2.5 kgm^2. Its angular velocity is increasing at the rate of 3.0 rad/s^2. What is the torque on the object? In N*m units

**Physics**

How much force does an 88 kg astronaut exert on his chair while sitting at rest on the launch pad? Answer: 860N Now the question: How much force does the astronaut exert on his chair while accelerating straight up at 14 m/s^2? What do you do first, how do you go about getting ...

**physics**

A loudspeaker of mass 24.0 {\rm kg} is suspended a distance of h = 2.20 {\rm m} below the ceiling by two cables that make equal angles with the ceiling. Each cable has a length of l = 3.30 {\rm m}. What is the tension T in each of the cables? Use 9.80 {\rm m/s}^2 for the magni...

**Physics**

Thank you!

**Physics**

A 1300 kg car is traveling along a straight road at 20 m/s. Two seconds later its speed is 24 m/s. What is the magnitude of the net force acting on the car during this time? I dont know what equation to use, and I keep getting stuck

**Physics**

Thank you very much!

**Physics**

A 2000 {\rm kg} car traveling at a speed of 13 {\rm m/s} skids to a halt on wet concrete where mu_k = 0.50. How long are the skid marks? I tried doing this many times and each answer is wrong. Can someone help?

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