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Juliette [100K]
3 years ago
14

Mary walked north from her home to Sheila's home, which is 4.0 kilometers away. Then she turned right and walked another 3.0 kil

ometers to the supermarket, which is 5.0 kilometers from her own home. She walked the total distance in 1.5 hours. What were her average speed and average velocity?
Physics
1 answer:
bixtya [17]3 years ago
8 0
The answer is speed: 4.7 km/h, velocity: 3.3 km/h.

Distances and time are given:
d1 =  4 km
d2 = 3 km
d3 = 5 km
t = 1.5 h

The speed can be expressed as a distance (d) divided by time (t). The average speed (s) is total distance travelled divided by time:
s = (d1 + d2)/t = (4+3)/1.5 = 7/1.5 = 4.7 km/h

The average velocity (v) is total displacement (d₁) from the starting point divided by time. Since Mary's starting point was home, and she walked to the supermarket, which is 5.0 kilometers from her own home, her displacement is 5 km:
v = d₁/t = 5/1.5 = 3.3 km/h

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According to the law of conservation of energy, mechanical energy can be changed to heat energy.
Leno4ka [110]

Answer:

The answer to this question is given below in this explanation section.

Explanation:

                     " law of conservation of energy"

The law of conservation of energy states that energy can neither be created nor destroyed only converted from one form of energy into another.This mean that a system always has a same account of a energy,unless it is added from the outside.This is particularly confusing in the case of non conversation forces,where energy is converted from ,mechanical energy into thermal energy.but the overall energy does remain the same.The only way to use energy is to transform energy from one form to another.

The amount of energy in any system than it is determined by the following equation.

Ut=Ui +W+Q

  • Ut is the total internal energy of a system.
  • Ui is the initial internal energy of a system.
  • W is the work done by or on the system.
  • Q is the heat added to or removed by the system.

It is also possible to determined the change in internal energy of the system using the equation.

ΔU=W+Q

The mechanical energy of a system increases provided their is no loss of energy due to friction.The energy would transform to kinetic energy when the speed is increasing.Te mechanical energy of a system remain constant provided their is no loss of energy due to friction.

The law of conversation of energy which say that in a closed system total energy is conserved that is it constant.

KE1 + PE1=KE2+PE2

 

8 0
2 years ago
Why it is difficult to run fast in sand​
balu736 [363]
Running on sand requires 1.6 times more energy spent than running on hard surface, so the force applied by our foot on sand is less.
8 0
3 years ago
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A car travels along a highway with a velocity of 24 m/s, west. The car exits the highway; and 4.0 s later, its instantaneous vel
zloy xaker [14]

Answer:

4.25 m/s^{2}

Explanation:

Change in velocity considering the x component will be

Final velocity-Initial velocity

\triangle v_x= 16cos 45^{\circ}-24=-12.6862915 m/s

Change in velocity considering the y component will be

Final velocity-Initial velocity

\triangle v_y= 16sin 45^{\circ}-0=11.3137085 m/s

Resultant change in velocity=\sqrt {(-12.6862915 m/s)^{2}+(11.3137085 m/s)^{2}}=16.9982938 m/s

Acceleration= change in velocity per unit time hence

a= \frac {16.9982938}{4}=4.24957345\approx 4.25 m/s^{2}

5 0
3 years ago
In the diagram, the wavelength is shown by :
MAXImum [283]

Answer:

i think the anwer is C

Explanation:

6 0
3 years ago
(a) How many fringes appear between the first diffraction-envelope minima to either side of the central maximum in a double-slit
Ainat [17]

Answer:

a

The number of fringe is  z  = 3 fringes

b

The  ratio is I = 0.2545I_o

Explanation:

a

 From the question we are told that

        The wavelength is  \lambda = 600 nm

        The distance between the slit is  d = 0.117mm = 0.117 *10^{-3} m

        The width of the slit is  a = 35.7 \mu m = 35.7 *10^{-6}m

let  z be the number of fringes that appear between the first diffraction-envelope minima to either side of the central maximum in a double-slit pattern is  and this mathematically represented as

             z = \frac{d}{a}

Substituting values

             z = \frac{0.117*10^{-3}}{35.7 *10^{-6}}  

             z  = 3 fringes

b

   From the question  we are told that the order  of the bright fringe is  n = 3

   Generally the intensity of  a pattern  is mathematically represented as

                 I = I_o cos^2 [\frac{\pi d sin \theta}{\lambda} ][\frac{sin (\pi a sin \frac{\theta}{\lambda } )}{\pi a sin \frac{\theta}{\lambda} } ]

Where I_o is the intensity  of the  central fringe

 And  Generally  sin \theta = \frac{n \lambda }{d}

               I = I_o co^2 [ \frac{\pi (\frac{n \lambda}{d} )}{\lambda} ] [\frac{\frac{sin (\pi a (\frac{n \lambda}{d} ))}{\lambda} }{\frac{\pi a (\frac{n \lambda}{d} )}{\lambda} } ]

               I = I_o cos^2 (n \pi)[\frac{\frac{sin(\pi a (\frac{n \lambda}{d} ))}{\lambda} )}{ \frac{ \pi a (\frac{n \lambda }{d} )}{\lambda} } ]

               I = I_o cos^2 (3 \pi) [\frac{sin (\frac{3 \pi }{6} )}{\frac{3 \pi}{6} } ]

                I = I_o (1)(0.2545)

                  I = 0.2545I_o

6 0
3 years ago
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