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liubo4ka [24]
3 years ago
10

a dump truck travels 70mph for 3 hours, then for 20mph for another 2 hours in the same direction. what is the average speed the

car traveled?
Physics
1 answer:
Dmitry_Shevchenko [17]3 years ago
8 0

Answer:

the average speed of the car is 170 mph.

Explanation:

Given;

initial speed, u = 70 mph

time of motion, t₁ = 3 hours

final speed, v = 20 mph

time of motion, t₂ = 2 hours

The average speed of the car is calculated as;

v' = \frac{70(3) - 20(2)}{3-2} \\\\v' = 170 \ mph

Therefore, the average speed of the car is 170 mph.

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Why would an object float in water, but sink in rubbing alcohol?
Romashka [77]

Because water is more dense than the object but rubbing alcohol is less dense than the object

6 0
3 years ago
Consider electrons of kinetic energy 6.0 eV and 600 keV. For each electron, find the de Broglie wavelength, particle speed, phas
irinina [24]

Answer:

For 6.0 eV

0.5 nm, 1.45*10^6 m/s, 6.17*10^10 m/s, 1.45*10^6 m/s

For 600 eV

1.26*10^-3 nm, 2.66*10^8 m/s, 3.37*10^8 m/s, 2.66*10^8 m/s

Explanation:

See attachment for calculation

5 0
3 years ago
A person throws a ball straight up. He releases the ball at a height of 1.75 m above the ground and with a velocity of 12.0 m/s.
Lyrx [107]

Answer:

a) 1.22 s

b) 9.089 m

Explanation:

t = Time taken

u = Initial velocity

v = Final velocity

s = Displacement

a = Acceleration due to gravity = 9.81 m/s²

v=u+at\\\Rightarrow t=\frac{v-u}{a}\\\Rightarrow t=\frac{0-12}{-9.81}\\\Rightarrow t=1.22\ s

Time taken by the ball to reach the highest point is 1.22 seconds

s=ut+\frac{1}{2}at^2\\\Rightarrow s=12\times 1.22+\frac{1}{2}\times -9.81\times 1.22^2\\\Rightarrow s=7.339\ m

The maximum height the ball will reach above the ground is 1.75+7.339 = 9.089 m

8 0
3 years ago
The source of a sound moves away from the listener. The listener has the impression that the source is __________.
prohojiy [21]

Explanation:

As the source of sound waves approaches you the sound waves get closer together, increasing their frequency and the pitch of the sound. The opposite happens when the source of sound waves moves away from you

6 0
2 years ago
Length of table is 1.0m,1.00m and 1.000m.Which one is more accurate?​
natita [175]

Answer:

1.00 m is a more accurate measured length.

Explanation:

Denote length of the table by L.

For L=1.0 m, there is one significant digit after the decimal.

Care 1: When one more significant digit after decimal considered, the exact number can be from 0.95 to 1.05.

So, the possible span of error \Delta E_1= 1.05-0.95= 0.1m

For L=1.00 m, there is two significant digits after the decimal.

Case 2: When one more significant digit after decimal considered, the exact number can be from 0.095 to 1.005.

So, the possible span of error \Delta E_2= 1.005-0.095= 0.01m

Case 3: For L=1.000 m, there is three significant digits after the decimal.

When one more significant digit after decimal considered, the exact number can be from 0.0095 to 1.0005.

So, the possible span of error \Delta E_3= 1.0005-0.0095= 0.001m

As \Delta E_1 >\Delta E_2>\Delta E_3

So, the least error is in the third case when L=1.00m, hence, L= 1.00m is more accurate.

6 0
2 years ago
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