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Darina [25.2K]
3 years ago
7

Sally and Ramona were competing in a four-lap, one-mile foot race. Sally’s style was to run at a constant rate of 12 mph. Ramona

decided to run her first three laps at 11 mph, and save a ‘kick’ in order to run a 16 mph pace for the fourth and final lap. Who wins the race, and by how many minutes or seconds?
Physics
1 answer:
svetoff [14.1K]3 years ago
7 0

Sally wins the race by 0.03 min

Explanation:

To find time = distance / velocity

Sally;

1 mile / 12 mph

= ¹/12 hrs * 60

= 5 min

Ramona;

³/4 mile ÷ 11 mph  +  ¹/4 mile ÷ 16 mph

= ³/44 hrs + ¹/64 hrs

= 4.09 min + 0.94 min

= 5.03 min

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If the speed of an object increases, the kinetic energy will ______________ because _____________________________________.
Svetlanka [38]
Increase because kinetic energy is all about the speed of an object and the more speed the more kinetic energy.
5 0
3 years ago
It's time to get a little more specific. Based on the velocity (Vx) graph for the car and the velocity data in the table, divide
UNO [17]

Answer:

0.2 – 4.6 seconds   increasing speed in positive direction

4.6 - 7.8 seconds   decelerating speed in a positive direction

8 - 17.2 seconds  accelerating speed in a negative direction

Explanation:

**Plato** **Edmentum**n~ this question is pretty open ended, so its hard to get it wrong honestly, good luck <3 ~

8 0
3 years ago
Um pls help<br><br>I really need help
Dima020 [189]

Answer:

1.8L

Explanation:

Boyle's law is a gas law, stating that the pressure and volume of a gas have an inverse relationship. If volume increases, then pressure decreases and vice versa, when the temperature is held constant.

So x is the volume at pressure 235

235x = 101(4.2)

x = 424.2/235 = 1.8

3 0
3 years ago
A spherical snowball is melting in such a way that its radius is decreasing at rate of 0.1 cm/min. At what rate is the volume of
andrew11 [14]

Answer:

\frac{dV}{dt}=-78,4\pi \frac{cm^{3} }{min}

Explanation:

Knowing that the volume of a sphere is V=(4/3)πr³ and \frac{dr}{dt}=-0.1\frac{cm}{min}

We must find \frac{dV}{dt}=? when r=14cm

V=(4/3)πr³ ⇒

\frac{dV}{dt}=\frac{4}{3}\pi3r^{2}\frac{dr}{dt}\\\frac{dV}{dt}=4\pi r^{2}(-0.1\frac{cm}{min})

and r=14cm then

\frac{dV}{dt}=4\pi(14cm)^{2}(-0.1\frac{cm}{min})\\\frac{dV}{dt}=4\pi196cm^{2}(-0.1\frac{cm}{min})\\\frac{dV}{dt}=-78,4\pi \frac{cm^{3} }{min}

Note: as you can see the relationship of change of r with respect to t is negative because it is a decrease, and also its volume ratio

4 0
4 years ago
Two train whistles have identical frequencies of 1.64 102 Hz. When one train is at rest in the station and the other is moving n
Amiraneli [1.4K]

Answer:

Vs = 6.73 m/s or Vs = 16.3 m/s

Explanation:

frequency of the trains whistle (f) = 1.64 x 10^{2} Hz = 164 Hz

frequency of beats heard = 4 beats/s = 4 Hz

velocity of the stationary train (Vr) = 0

velocity of sound in air (V) = 343 m/s

velocity of the moving train (Vs) = ?

we can get the velocity of the moving train from the formula below

Fn = f x \frac{V + Vr}{V - Vs} ...equation 1

where Fn = net frequency

  • case one - assuming the train is approaching the station Fn =  164 + 4 = 168 Hz

substituting the known values into equation 1

168 =  164 x \frac{343 + 0}{343 - Vs}

1.02 = \frac{343 + 0}{343 - Vs}

Vs = 343 - \frac{343 + 0}{1.02}

Vs = 6.73 m/s

  • case two - assuming the train is leaving the station Fn =  164 - 4 = 160 Hz

substituting the known values into equation 1

168 =  160 x \frac{343 + 0}{343 - Vs}

1.05 = \frac{343 + 0}{343 - Vs}

Vs = 343 - \frac{343 + 0}{1.05}

Vs = 16.3 m/s

6 0
4 years ago
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