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aliina [53]
3 years ago
12

A cyclist rides 4.0 km due west, then 12.0 km 33° west of north. From this point she rides 9.0 km due east. What is the final di

splacement from where the cyclist started (in km)? (Express your answer in vector form. Assume the +x-axis is to the east, and t
Physics
1 answer:
IgorC [24]3 years ago
5 0

Answer:

\mathbf{r = (-5.064   \ \hat i + 6.536 \ \hat j) km}

Explanation:

Given that:

A cyclist rides 4.0 km due west, then 12.0 km 33° west of north. From this point she rides 9.0 km due east.

Let:

r_1 = 4.0  \ km \ due \ west \\ \\ r_2 = 12.0 \  km \  \ \ \ \  \theta = 33^0 \ west \ of \ north \\ \\ r_3 = 9.0 \ km \ due  \ east

Assuming that:

east is the + x axis  and has a unit vector of \hat i

north is the +y axis and has a unit vector of \hat j

west is the - x axis and has a unit vector of -\hat {i}

south is the - y axis and has a unit vector of -\hat j

The displacement r_x in a given direction of x can be expressed by the formula:

r_x = \sum r_i

r_x = -4-12 cos (33)+9

r_x = - 5.064 \ km

The displacement r_y in a given direction of y can be expressed by the formula:

r_y = \sum r_j

r_y = 12  \ \ * s in (33)

r_y = 6.536 \ km

The final displacement can be expressed by the relation;

r = r_x \hat i + r_y \hat j

\mathbf{r = (-5.064   \ \hat i + 6.536 \ \hat j) km}

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A hot-air balloon plus cargo has a mass of 308 kg and a volume of 2910 m3 on a day when the outside air density is 1.22 kg/m3. T
lesya [120]

9514 1404 393

Answer:

  1.114 kg/m³

Explanation:

The total mass of the air in the balloon and the balloon + cargo will be the mass of the displaced air. If d is the density of the air in the balloon, then we have ...

  2910d +308 = 2910×1.22

Solving for d, we find ...

  2910d = 2919(1.22) -308

  d = 1.22 -308/2910

  d ≈ 1.114 . . . kg/m³

The density of the hot air is about 1.114 kg/m³.

6 0
3 years ago
The potential difference between the plates of a capacitor is 145 V. Midway between the plates, a proton and an electron are rel
aniked [119]

Answer:

= 2.52 x 10^ 6 m/s        

Explanation:

The force that acts on charged particles between capacitor plates =

F = (q) (Δv)  ÷ d

Here,  d = distance between the two plates

          q = charge of the charged particle

         Δv = voltage

Normally, the force that makes both proton and electron released from rest, giving the charge acceleration is F=m X a. where m= mass and a = acceleration

Poting this equation with the first one, we have:

m X a =  (q) (Δv)  ÷ d

So, the acceleration of a proton when moving towards a negatively charged plate is

a = (q) (Δv)  ÷ (d) (m) {proton}

Likewise, the acceleration of an electron when moving towards a positively charged plate is

a = (q) (Δv)  ÷ (d) (m) {electron}

Dividing the proton acceleration formula by the electron acceleration formula we have:

a (proton) / a (electron) = m (proton) / m(electron)

inserting equation of motion to get distance, s

s = ut + 1/2 at^2

recall that electron travel distance, d/2

d/2 = 1/2 at^2

making t the subject of the formula

we have, t =√(d ÷ a(electron))

The distance of proton:

d/2 =  ut + 1/2 at^2 [proton}

put d/2 =  ut + 1/2 at^2 [proton} into t =√(d ÷ a(electron))

Initial speed, ui = √(d ÷ a(electron)) = (d/2) - (1/2) x (d) (a(proton) + a(electron))

since acceleration wasn't given in the question, lets use mass(elect

ron)  ÷ mass(proton) rather than use (a(proton) + a(electron))

Therefore, intial speed= 1/2√((e X Δv) ÷ m(electron)) (1- m(electron)/ m(proton))

   Note, e = 1.60 x 10^-19

           m(electron) = 9.11 X 10^-31

            m(proton) = 1.67  X 10^-27

Input these values into the formula above, initial speed, UI =  

           = 2.52 x 10^ 6 m/s          

7 0
3 years ago
Read the scenario. A car travels 25 m/s forward for 10 s. Which option accurately identifies the measurements within the scenari
Phantasy [73]

Explanation:

It is given that,

A car travels 25 m/s forward for 10 s.

Solution,

For a vector, a quantity must have both magnitude as well as the direction. For a scalar, a quantity have only the magnitude. In this case, the car moves in forward direction.  This is the only difference between the vector and the scalar.

Out of given option,s the correct option is (c) "The measurement 25 m/s is the only vector quantity because it is a measurement of speed".

5 0
3 years ago
Name two examples where the cohesive force dominates over the adhesive force and vice versa​
lidiya [134]
Attractive forces between molecules of the same type are called cohesive forces. ... Attractive forces between molecules of different types are called adhesive forces. Such forces cause liquid drops to cling to window panes, for example.
5 0
3 years ago
1.) A ball is thrown horizontally from the top of a building. What is the vertical velocity of the ball after 1 second?
BARSIC [14]
  1. 9.8
  2. zero
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  5. Uniform accelerated motion
6 0
3 years ago
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