A 0.21 kg hockey puck has a velocity of 2.2 m/s toward the east (the +x direction) as it slides over the frictionless surface of an ice hockey rink. What are the:

(a) magnitude and (b) direction of the constant net force that must act on the puck during a 0.43 s time interval to change the puck's velocity to 3.7 m/s toward the west?

and what are the:

(c) magnitude and (d) direction if, instead, the velocity is changed to 3.7 m/s toward the south?

Give your directions as positive (counterclockwise) angles measured from the +x direction.

A red ball is thrown down with an initial speed of 1.3 m/s from a height of 27 meters above the ground. Then, 0.5 seconds after the red ball is thrown, a blue ball is thrown upward with an initial speed of 24.8 m/s, from a height of 0.7 meters above the ground. The force of gravity due to the earth results in the balls each having a constant downward acceleration of 9.81 m/s².

1) What is the speed of the red ball right before it hits the ground?

m/s

Your submissions:

• 23

Computed value:

23

Submitted:

Correct!

2) How long does it take the red ball to reach the ground?

s

Your submissions:

• 2.2

Computed value:

2.2

Submitted:

Correct!

3)

What is the maximum height the blue ball reaches?

m

Your submissions:

• 32.07

Computed value:

32.07

Submitted:

Correct!

4) What is the height of the blue ball 2 seconds after the red ball is thrown?

5) How long after the red ball is thrown are the two balls in the air at the same height?

6) Which statement is true regarding the blue ball?

After it is released and before it hits the ground, the blue ball is always moving faster than the red ball at any given time.

After it is released and before it hits the ground, the blue ball is sometimes moving faster than the red ball at any given time.

After it is released and before it hits the ground, the blue ball is never moving faster than the red ball at any given time.

7) Which statement is true about the red ball?

The acceleration is positive and it is speeding up

The acceleration is negative and it is speeding up

The acceleration is positive and it is slowing down

The acceleration is negative and it is slowing down

A pot of hot water is boiling on your stove.  The pot is in the shape of a round cylinder made of aluminum which is 10 cm in radius.  The aluminum is 3 mm thick.  You notice that after 22 minutes, 0.13 kg of water has boiled away.

A. What is the temperature of the inner surface of the bottom of the pot?

B. How much energy is required to boil away M kg of water?

C. What is the difference in temperature between the inner and outer sufaces of the aluminum bottom of the pot?

D. What is the change in entropy of the boiling water after boiling away 0.13 kg of water?

The figure is a section of a conducting rod of radius R₁ = 1.20 mm and length L = 13.80 m inside a thin-walled coaxial conducting cylindrical shell of radius R₂ = 10.1R₁ and the (same) length L. The net charge on the rod is Q₁ = +3.41 × 10^-12 C; that on the shell is Q₂ = -2.33Q₁. What are the (a) magnitude E and (b) direction (radially inward or outward) of the electric field at radial distance r = 2.10R₂? What are (c) E and (d) the direction at r = 5.31R₁? What is the charge on the (e) interior and (f) exterior surface of the shell?

A 75.0 kg ice hockey goalie, originally at rest, catches a 0.150 kg hockey puck slapped at him at a velocity of 18.0 m/s. Suppose the goalie and the ice puck have an elastic collision and the puck is reflected back in the direction from which it came. What would their final velocities (in m/s) be in this case? (Assume the original direction of the ice puck toward the goalie is in the positive direction. Indicate the direction with the sign of your answer.)

puck ____ m/s

goalie ____ m/s

An 80 kg skydiver falls through air with a density of 1.15 kg/m3 . Assume that his drag coefficient is C=0.57. When he falls in the spread-eagle position his body presents an area A1=0.94 m2 to the wind, whereas when he dives head first, with arms close to the body and legs together his area is reduced to A2=0.21 m2 . What are the terminal speeds in both cases?

In a particular Millikan oil-drop apparatus, the plates are 2.25 cm apart. The oil used has a density of 0.815 g/cm3 , and the atomizer that sprays the oil drops produces drops of diameter 1.00×10⁻³ mm.  

A) What strength of electric field is needed to hold such a drop stationary against gravity if the drop contains five extra electrons?

B) What should be the potential difference across the plates to produce this electric field?

C) If another drop of the same oil requires a plate potential of 65.3 V to hold it stationary, how many excess electrons did it contain?

Imagine a universe that has a permitivity of ε = 3εo. Within this infinite space, you find a spherical distribution of charge of radius a that has a volumetric charge density of ρv = ( a r ) Cm−3 . a. Determine the expressions for the electric field inside and outside this spherical region. b. Determine an equation that represents the energy required to put together this distribution of charge. c. If a = 2 m, what is this energy equal to in Joules?

A solid, uniform disk of radius 0.250 m and mass 53.2 kg rolls down a ramp of length 4.70 m that makes an angle of 12.0° with the horizontal. The disk starts from rest from the top of the ramp.

(a) Find the speed of the disk's center of mass when it reaches the bottom of the ramp. m/s

(b) Find the angular speed of the disk at the bottom of the ramp. rad/s

One of the largest contributions to modern electronics came from a man named Nikola Tesla. Briefly research Nikola Tesla's origins and his scientific discoveries and present your results in point form.

explain electric charge and electric field. Also give examples.

please not by hand

an object 3.0cm high object is place 4.0cm in front of a converging lens with a focal length of 8.0cm. the object is located on the principal axis.

part 1. the image that will be formed will be . real, virtual or neither?

part 2. the image will be loacted on the same side of the lens at a distance of __ from the lens?

part 3. the magnification of the image will be ?

part 4. the size of the image (in cm) will be ?

Question 56)

PART 1)

In the figure an electron is shot at an initial speed of v0 = 4.62 × 106 m/s, at angle θ0 = 40.9 ˚ from an x axis. It moves through a uniform electric field = (5.40 N/C). A screen for detecting electrons is positioned parallel to the y axis, at distance x = 1.84 m. What is the y component of the electron's velocity (sign included) when the electron hits the screen?

PART 2)

In the figure a nonconducting rod of length L = 8.34 cm has charge -q = -4.42 fC uniformly distributed along its length. (a) What is the linear charge density of the rod? What are the (b) magnitude and (c) direction (positive angle relative to the positive direction of the x axis) of the electric field produced at point P, at distance a = 13.7 cm from the rod? What is the electric field magnitude produced at distance a = 63 m by (d) the rod and (e) a particle of charge -q = -4.42 fC that replaces the rod?

You will get a positive vote for answering both parts of this problem correctly! I really need help!

In terms of λ, f, μ, and T what times the square root of the tension is equal to the wavelength?

Please show work, thanks.