Thursday

July 31, 2014

July 31, 2014

Total # Posts: 26

**Physics**

when I set 1/2mv2 equal to 1/2kx2 I got .366

**Physics**

x = v * sqrt(m/k) correct?

**Physics**

I did m1v1 /(m1+m2) = vf = .252723 x = vf(m/k) x = .366

**Physics**

A 0.409 kg block is attached to a horizontal spring that is at its equilibrium length, and whose force constant is 19.5 N/m. The block rests on a frictionless surface. A 0.0500 kg wad of putty is thrown horizontally at the block, hitting it with an initial speed of 2.32 m/s an...

**Physics**

I got KE = 4.622 J and it isn't correct

**Physics**

The collision between a hammer and a nail can be considered to be approximately elastic. Estimate the kinetic energy acquired by a 13 g nail when it is struck by a 550 g hammer moving with an initial speed of 4.1 m/s. I am completely confused by this problem all of my answers ...

**Physics**

You are holding a shopping basket at the grocery store with two 0.51 kg cartons of cereal at the left end of the basket. The basket is 0.73 m long. Where should you place a (1.8 kg) half gallon of milk, relative to the left end of the basket, so that the center of mass of your...

**Physics**

Suppose now that the air carts below are both moving to the right initially. The cart to the left has a mass m1 and an initial speed v0; the cart to the right has an initial speed v0/2. If the center of mass of this system moves to the right with a speed 6/7 multiplied by v0, ...

**Physics**

A child sits in a wagon with a pile of 0.60 kg rocks. If she can throw each rock with a speed of 10 m/s relative to the ground, causing the wagon to move, how many rocks must she throw per minute to maintain a constant average speed against a 3.7 N force of friction? I got .61...

**Physics**

During a rescue operation, a 5350 kg helicopter hovers above a fixed point. The helicopter blades send air downward with a speed of 59.0 m/s. What mass of air must pass through the blades every second to produce enough thrust for the helicopter to hover?

**Physics**

A 2.1 kg block slides with a speed of 1.1 m/s on a frictionless, horizontal surface until it encounters a spring. (a) If the block compresses the spring 5.7 cm before coming to rest, what is the force constant of the spring? (b) What initial speed should the block have to comp...

**Physics**

A 0.47 kg pendulum bob is attached to a string 1.2 m long. What is the change in the gravitational potential energy of the system as the bob swings from point A to point B where θ = 31°? I've tried using PE = mgh but I don't know where the 31 degrees comes in ...

**Physics**

A 2.1 kg block slides with a speed of 1.1 m/s on a frictionless, horizontal surface until it encounters a spring. (a) If the block compresses the spring 5.7 cm before coming to rest, what is the force constant of the spring? (b) What initial speed should the block have to comp...

**Physics**

I am just so confused by this problem. I have done other problems with ease and I'm having so much trouble with other ones.

**Physics**

KE initial = 0 PE initial = mgh = 68.8662 = KE final KE final = 1/2mv2 v = 23.01 That isn't right. What have I done wrong?

**Physics**

A 0.26 kg rock is thrown vertically upward from the top of a cliff that is 27 m high. When it hits the ground at the base of the cliff the rock has a speed of 24 m/s. (a) Assuming that air resistance can be ignored, find the initial speed of the rock. (b) Find the greatest hei...

**Physics**

thank you, I got it

**Physics**

I'm still confused. How does that equal 1/2mv2 and how does that solve the problem.

**Physics**

At a playground, a 18.7 kg child plays on a slide that drops through a height of 2.07 m. The child starts at rest at the top of the slide. On the way down, the slide does a nonconservative work of -318 J on the child. What is the child's speed at the bottom of the slide? I...

**Physics**

I HAVE THE ANSWER. THANK YOU

**Physics**

At a playground, a 18.7 kg child plays on a slide that drops through a height of 2.07 m. The child starts at rest at the top of the slide. On the way down, the slide does a nonconservative work of -318 J on the child. What is the child's speed at the bottom of the slide? I...

**Physics**

Thank you, I understand that now.

**Physics**

1) my teacher is really bad. 2) Is delta potential energy = mgvf - mgvi

**Physics**

Catching a wave, a 65 kg surfer starts with a speed of 1.3 m/s, drops through a height of 2.10 m, and ends with a speed of 8.2 m/s. How much nonconservative work was done on the surfer? I have genuinely no idea how to solve this problem.

**Physics**

That's why I was getting it wrong. I kept using delta x which was one in both cases. Have I mentioned you are a lifeseaver.

**Physics**

The work required to stretch a certain spring from an elongation of 4.11 cm to an elongation of 5.11 cm is 32.0 J. (a) Is the work required to increase the elongation of the spring from 5.11 cm to 6.11 cm greater than, less than, or equal to 32.0 J? (b) Verify your answer to p...

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