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3 years ago

You drive a car for 2.0 h at 60 km/h, then for another 3.0 h at 85 km/h. What is your average velocity

Physics

1 answer:

Anon25 [30]3 years ago

8 0

Answer:

Explanation:

Average velocity is found in the total displacement experienced in the trip divided by the total time it took to make this trip. If, for the first 2.0 hours, the car travels at 60 km/hr, then in 2.0 hours the car can travel 120 km; if it then travels for 3.0 at 85 km/hr, it can travel 255 km in the same direction. The total time this took was 5.0 hours. So doing the math and rounding correctly by following the rules for the adding and subtracting of sig fig's:

$v=\frac{120+255}{5.0}=\frac{380}{5.0}=76\frac{km}{hr}$

If you do not round when you add, the average velocity is 75 km/hr

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A 51.0 kg crate, starting from rest, is pulled across a floor with a constant horizontal force of 225 N. For the first 10.0 m th

shepuryov [24]

Answer:

The final speed of the crate is 12.07 m/s.

Explanation:

For the first 10.0 meters, the only force acting on the crate is 225 N, so we can calculate the acceleration as follows:

$F = ma$

$a = \frac{F}{m} = \frac{225 N}{51.0 kg} = 4.41 m/s^{2}$

Now, we can calculate the final speed of the crate at the end of 10.0 m:

$v_{f}^{2} = v_{0}^{2} + 2ad_{1}$

$v_{f} = \sqrt{0 + 2*4.41 m/s^{2}*10.0 m} = 9.39 m/s$

For the next 10.5 meters we have frictional force:

$F - F_{\mu} = ma$

$F - \mu mg = ma$

So, the acceleration is:

$a = \frac{F - \mu mg}{m} = \frac{225 N - 0.17*51.0 kg*9.81 m/s^{2}}{51.0 kg} = 2.74 m/s^{2}$

The final speed of the crate at the end of 10.0 m will be the initial speed of the following 10.5 meters, so:

$v_{f}^{2} = v_{0}^{2} + 2ad_{2}$

$v_{f} = \sqrt{(9.39 m/s)^{2} + 2*2.74 m/s^{2}*10.5 m} = 12.07 m/s$

Therefore, the final speed of the crate after being pulled these 20.5 meters is 12.07 m/s.

I hope it helps you!

7 0

3 years ago

A ball hits a wall horizontally at 6m/s and rebounces at 4.4m/s the ball is in contact with wall for 0.04 sec. what is the accel

Svetlanka [38]

Answer:

Acceleration (a) = 40 m/s²

Explanation:

Given:

Initial velocity (u) = 6 m/s

Final velocity (v) = 4.4 m/s

Time taken (t) = 0.04sec

Find:

Acceleration (a) = ?

Computation:

We know that,

⇒ v = u + at

⇒ a = (v - u) / t

⇒ Acceleration (a) = (4.4 - 6) / 0.04

⇒ Acceleration (a) = (-1.6) / 0.04

Acceleration (a) = 40 m/s²

8 0

3 years ago

What occurs when light bends while passing from one medium to another?

Levart [38]

Answer:So the answer is B

Explanation: When the light rays either bend or change their direction while passing from one medium to another it is called refraction of light. The refraction of light takes place when light travels from air into glass, from glass into air, from air into water or from water into air.

7 0

3 years ago

1. A wave has a wavelength of 5 m and a frequency of 2 Hz. At what speed/velocity does the

yuradex [85]

Answer:

1.10m/s

2.0.1m

3.5Hz

Explanation:

v=velocity, f=frequency and T=wavelength

1.v=ft

v=2x5

=10m

2.v=ft

100=1000T

divide both sides by 1000

T=0.1m

3.v=fT

25=5f

divide both sides by 5

f=5Hz

4 0

3 years ago

The ph of an acidic substance ia between what values on the ph scale

aalyn [17]

0 - 6 is acidic

7 is neutral

8 - 14 is basic

7 0

3 years ago