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Vedmedyk [2.9K]
3 years ago
12

A 65-kg ice skater stands facing a wall with his arms bent and then pushes away from the wall by straightening his arms. At the

instant at which his fingers lose contact with the wall, his center of mass has moved 0.45m , and at this instant he is traveling at 3.0m/s .
A. What are the average force exerted by the wall on him?.
B. What are the work done by the wall on him?.
C. What are the change in the kinetic energy of his center of mass?
Physics
1 answer:
Hitman42 [59]3 years ago
8 0

Answer:

A) F=650N

B) W=0J

C) \Delta K=292.5J

Explanation:

A) Considering the equation v_f^2=v_i^2+2ad, we can calculate:

F=ma=m\frac{v_f^2}{2d}=(65kg)\frac{(3m/s)^2}{2(0.45m)}=650N

B) The work the wall does is 0J, because the fingers of the scater against it do not move. It's the muscles on his arm that do the work.

C)\Delta K=K_f-K_i=\frac{mv_f^2}{2}-\frac{mv_i^2}{2}=\frac{(65kg)(3m/s)^2}{2}-\frac{(65kg)(0m/s)^2}{2}=292.5J

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One of the main factors driving improvements in the cost and complexity of integrated circuits (ICs) is improvements in photolit
nika2105 [10]

Answer:

0.000003782 m

0.000001891 m

0.000001197125 m

Explanation:

\lambda = Wavelength = 248 nm

D = Diameter of beam = 1 cm

f = Focal length = 0.625 cm

The angle is given by

\theta=\dfrac{1.22\lambda}{D}

The width is given by

d=2\theta f\\\Rightarrow d=2\dfrac{1.22\lambda f}{D}\\\Rightarrow d=2\dfrac{1.22\times 248\times 10^{-9}\times 6.25\times 10^{-2}}{1\times 10^{-2}}\\\Rightarrow d=0.000003782\ m

The required width is 0.000003782 m

Minimum resolvable line separation is given by

\dfrac{0.000003782}{2}=0.000001891\ m

The minimum resolvable line separation between adjacent lines is 0.000001891 m

when \lambda=157\ nm

d=2\dfrac{1.22\times 157\times 10^{-9}\times 6.25\times 10^{-2}}{1\times 10^{-2}}\\\Rightarrow d=0.00000239425\ m

The new minimum resolvable line separation between adjacent lines is

\dfrac{0.00000239425}{2}=0.000001197125\ m

6 0
3 years ago
What was Galileo’s contribution to the study of motion?
babunello [35]

Before giving you the answer straight away, I’d like to make sure you understand each option.


FIRST OPTION


“He developed the three laws of motion."


This option is not only the incorrect answer, but it is an incorrect statement. Galileo did not develop the three laws of motion. Isaac Newton was the one to compiled the three laws of motion.


SECOND OPTION


“He was the first to systematically study force and motion."


This option is a statement is true, and it could also be the correct answer. Galileo Galilei used experiments to search for the cause of motion.


THIRD OPTION


“He was the first to discover gravity."


This option is not only the incorrect answer, but it is an incorrect statement. Galileo was not the person to discover gravity. Sir Isaac Newton was the first to discover gravity.


FINAL OPTION


“He improved on Newton's laws."


This option is not only the incorrect answer, but it is an incorrect statement. Galilei did not improve Sir Isaac Newton’s laws.


Now that we’ve gone through each of the options individually, we can go ahead and determine the correct answer to the question, which is...


B ) He was the first to systematically study force and motion.



- Marlon Nunez

8 0
3 years ago
Read 2 more answers
Calculate the speed of a bike rider who accelerates (from rest) for 5 seconds down a hill at an acceleration of 8
olya-2409 [2.1K]

Answer:

speed=abs(v)=40ms^-1

Explanation:

acceleration, a = (v-u)/t

since initial velocity u=0 (at rest) and a=8ms^-2,

8=v/5

hence after 5 seconds, v=40ms^-1

6 0
3 years ago
Find the resistance of a wire of length 0.65m, 0.2mm and resistivity 3X10^-6 ohm metre.​
const2013 [10]

Answer:

hope this is help full

7 0
3 years ago
A linear network has a current input 7.5 cos(10t + 30°) A and a voltage output 120 cos(10t + 75°) V. Determine the associated im
Leona [35]

Answer:

16∠45° Ω

Explanation:

Applying,

Z = V/I................... Equation 1

Where Z = Impedance, V = Voltage output, I = current input.

Given: V = 120cos(10t+75°), = 120∠75°,  I = 7.5cos(10t+30) = 7.5∠30°

Substitute these values into equation 1

Z = 120cos(10t+75°)/7.5cos(10t+30)

Z = 120∠75°/ 7.5∠30°

Z = 16∠(75°-30)

Z = 16∠45° Ω

Hence the impedance of the linear network is 16∠45° Ω

8 0
3 years ago
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