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cluponka [151]
3 years ago
10

A football player runs 20 meters North of a football field, and then 15 meters East. The total motion lasted 15 seconds. What wa

s his average speed
Physics
1 answer:
vlada-n [284]3 years ago
4 0
Given:
1st run: 20 meters North
2nd run: 15 meters East
time: 15 seconds

Average speed = total distance covered / total time taken
Ave. Speed = (20m + 15m) / 15s
Ave. Speed = 35m / 15s
Ave. Speed = 2 1/3  meters per second
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A force of 35 N acts on a ball for 0.2 s. If the ball is initially at rest:
olya-2409 [2.1K]

To solve this problem we will apply the concepts related to momentum and momentum on a body. Both are equivalent values but can be found through different expressions. The impulse is the product of the Force for time while the momentum is the product between the mass and the velocity. The result of these operations yields equivalent units.

PART A ) The Impulse  can be calculcated as follows

L= F\Delta t

Where,

F = Force

\Delta t =Change in time

Replacing,

L = (35N)(0.2s)

L= 7N\cdot s

PART B) At the same time the momentum follows the conservation of momentum where:

Initial momentum= Final momentum

And the change in momentum is equal to the Impulse, then

\Delta p = L

And

\Delta p = p_f - p_i

There is not initial momentum then

\Delta p = p_f

L = p_f

p_f = 7N\cdot s = 7kg\cdot m/s

8 0
3 years ago
A skydiver reaches terminal velocity. Then he opens his parachute.
schepotkina [342]

Answer:

it is 0.9999.10896

Explanation:

4 0
2 years ago
Read 2 more answers
A heat-conducting rod consists of an aluminum section, 0.30 m long, and a copper section, .70m long. Both sections have a cross-
Igoryamba
Thermal conductions
K= QL/ART
Aluminium T₁ = 10 + 273.15
                    T₂ = 283.15k
205 = 2.0  × 0.30/4× 10⁻⁴ × (T₂ - 283.15)
Copper
385 = Q × 0.70/4×10⁻⁴ ×(433.15 - T₂)
Where T₃ = 160 + 273.15
T₃ = 433.15K
From 2 to 3
205/385 = 0.30/0.70 × 433.15 - T₂/T₂ - 283.15
= 0.53T₂ -150.06 = 181.92 - 0.42 T₂
→ 0.95T₂ = 331.98 ⇒ T₂ = ₂349.45k
T₂ = 76.3°c
=77°c.

6 0
3 years ago
A 14.0 gauge copper wire of diameter 1.628 mmmm carries a current of 12.0 mAmA . Part A What is the potential difference across
NARA [144]

Answer:

a) 2.063*10^-4

b) 1.75*10^-4

Explanation:

Given that: d= 1.628 mm = 1.628 x 10-3 I= 12 mA = 12.0 x 10-8 A The Cross-sectional area of the wire is:  

A=\frac{\pi }{4}d^{2}  \\=\frac{\pi }{4}*(1.628*10^-3 m)^2\\=2.082*10^-6 m^2\\

a) <em>The Potential difference across a 2.00 in length of a 14-gauge copper  </em>

<em>    wire: </em>

  L= 2.00 m

From Table  Copper Resistivity p= 1.72 x 10-8 S1 • m The Resistance of the Copper wire is:

R=\frac{pL}{A}

   =0.0165Ω

The Potential difference across the copper wire is:  

V=IR

 =2.063*10^-4

b) The Potential difference if the wire were made of Silver: From Table: Silver Resistivity p= 1.47 x 10-8 S1 • m

The Resistance of the Silver wire is:  

R=\frac{pL}{A}

   =0.014Ω

The Potential difference across the Silver wire is:  

V=IR

 =1.75*10^-4

4 0
3 years ago
The gnaphosid spider Drassodes cupreus has evolved a pair of lensless eyes for detecting polarized light. Each eye is sensitive
BartSMP [9]

Answer:

Part A

The intensity is  I = 618 W/m^2  

Part B

The intensity is  I_1= 81.884 W/m^2

Explanation:

From the question we are told that

       The intensity of the light detected by first eye is I = 700 W/m^2

Now at initial state according the question the light  ray is perpendicular to the eye so it means that it is at 90° the eye

Now the first question is to obtain the intensity the first eye (the first in this case is the one focused on the light  )would detect when the head is rotated by 20°  its previous orientation

This  is mathematically evaluated  as

                   I = I_i cos^2 ( 20^o)

                    I = 700\  cos^2 (20)

                    I = 618 W/m^2  

Now the second  question is to obtain the intensity the first eye (the first eye  in this case is the one that is not  focused on  the light  )would detect when the head is rotated by 20°  its previous orientation

Now in this case the angle between the eye and the light is 90-20 = 70°

           So

               I_1 = 700 \  cos^2 (70)

                   I_1= 81.884 W/m^2

 

5 0
3 years ago
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