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3 years ago

A man walks 30 m to the west than 5 m to the east in 45 seconds.

Physics

1 answer:

harkovskaia [24]3 years ago

4 0

Answer:

35 m

0.56 m/s west

Explanation:

A) Total distance is the length of the path taken.

30 m + 5 m = 35 m

B) Velocity is displacement over time. Displacement is the difference between the final position and the initial position.

If west is -x, and east is +x, then:

Δx = -30 m + 5 m

Δx = -25 m

v = Δx / t

v = -25 m / 45 s

v = -0.56 m/s

v = 0.56 m/s west

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If a train travels 500 kilometers from Stockholm to

o-na [289]

Hello,

Average speed is total distance divided by total time. From the problem, our total distance is given as 500 kilometers and given time is 5 hours. Therefore, the average speed is:

$\displaystyle{v_\text{average}=\sum_{i=1}^n \dfrac{s_i}{t_i}}\\\\\displaystyle{v=\dfrac{500\ \text{km}}{5 \ \text{h}}}\\\\\displaystyle{v=100 \ \text{km/h}}$

Therefore, the average speed is 100 km/h. Please let me know if you have any questions!

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9 months ago

A student holds a bike wheel and starts it spinning with an initial angular speed of 9.0 rotations per second. The wheel is subj

KATRIN_1 [288]

Answer:

$\Delta t = 8 s$

Explanation:

As we know that the angular acceleration of the wheel due to friction is constant

so we can use kinematics

$\theta = \omega_i t + \frac{1}{2}\alpha t^2$

so we have

$(65 \times 2\pi) = (2\pi \times 9)(10) + \frac{1}{2}(\alpha)(10^2)$

$130\pi = 180\pi + 50 \alpha$

$\alpha = -\pi rad/s^2$

now time required to completely stop the wheel is given as

$\omega_f = \omega_i + \alpha t$

$0 = (2\pi \times 9) + (-\pi) t$

$t = 18 s$

now time required to stop the wheel is given as

$\Delta t = 18 - 10$

$\Delta t = 8 s$

6 0

2 years ago

A constant friction force of 25 N acts on a 65-kg skier for 15 s on level snow. What is the skier’s change in velocity

nikdorinn [45]

Answer:

$\Delta v=5.77m/s$

Explanation:

Newton's 2nd Law relates the net force F on an object of mass m with the acceleration a it experiments by F=ma. In our case the net force is the friction force, since it's the only one the skier is experimenting horizontally and the vertical ones cancel out since he's not moving in that direction. Our acceleration then will be:

$a=\frac{F}{m}$

Also, acceleration is defined by the change of velocity $\Delta v$ in a given time t, so we have:

$a=\frac{\Delta v}{t}$

Since we want the change in velocity, mixing both equations we conclude that:

$\Delta v=at=\frac{Ft}{m}$

Which for our values means:

$\Delta v=\frac{Ft}{m}=\frac{(25N)(15s)}{(65Kg)}=5.77m/s$

4 0

3 years ago

The pressure of a fluid at a specific depth depends only on the type of fluid?

timurjin [86]

I think yes the density

5 0

2 years ago

Answer the following questions.

Sever21 [200]

Answer:

1. B 2. A. 3. A. 4. B 5.B

Explanation:

1) The statement is false, because the acceleration (by definition) is the rate of change of velocity, which is a vector.

As a vector, it can change the magnitude, the direction, or both. As the speed is only the magnitudde, there can be an acceleration at constant speed, as in an uniform circular movement, where the acceleration produces a change in direction, not in the speed.

2) If the body is in motion (assuming that it is only translational motion) the position (displacement from the origin) must be change with time, so the statement is true.

3) This is true, as the acceleration, as we said above, is the rate of change of the velocity vector.

4) The statement is false, as an object moving at constant speed along a straight line is in movement, and is not accelerated at all.

5) The statement is false, as a body can momentarily come to an stop (before changing direction, for instance), and be accelerated at the same time.

The best example is an object thrown up in the air: once released, the only force acting on it is gravity, which produces an acceleration in opposite direction to the initial speed, until it causes the object to stop, change direction, and finally fall freely.

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3 years ago