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3 years ago

14

What is static and sliding friction

1 answer:

vodka [1.7K]3 years ago

5 0

Static friction is the friction that exists between a stationary object and the surface on which it's resting.
frictional force occurs when you try to push an object alongside a surface.

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A boy im50kg at rest on a skateboard is pushed by another boy who exerts a force of 200 N on him. If the first boy's

sergey [27]

Answer:

Time, t = 2 seconds

Explanation:

Given the following data;

Mass, m = 50 kg

Initial velocity, u = 0 m/s (since it's starting from rest).

Final velocity, v = 8 m/s

Force, F = 200 N

To find the time, we would use the following formula;

$F = \frac {m(v - u)}{t}$

Making time, t the subject of formula, we have;

$t = \frac {m(v - u)}{F}$

Substituting into the formula, we have;

$t = \frac {50(8 - 0)}{200}$

$t = \frac {50*(8)}{200}$

$t = \frac {400}{200}$

Time, t = 2 seconds

5 0

3 years ago

A car is designed to get its energy from a rotating

nydimaria [60]

Answer:

(a). The kinetic energy stored in the fly wheel is 46.88 MJ.

(b). The time is 1.163 hours.

Explanation:

Given that,

Radius = 1.50 m

Mass = 475 kg

Power $P= 15.0 hp = 15.0\times746=11190 watt$

Rotational speed = 4000 rev/min

We need to calculate the moment of inertia

Using formula of moment of inertia

$I=\dfrac{1}{2}mr^2$

Put the value into the formula

$I=\dfrac{1}{2}\times475\times(1.50)^2$

$I=534.375\ kg m^2$

(a). We need to calculate the kinetic energy stored in the fly wheel

Using formula of K.E

$K.E=\dfrac{1}{2}I\omega^2$

Put the value into the formula

$K.E = \dfrac{1}{2}\times534.375\times(4000\times\dfrac{2\pi}{60})^2$

$K.E=46880620.9\ J$

$K.E =46.88\times10^{6}\ J$

$K.E =46.88\ MJ$

(b). We need to calculate the length of time the car could run before the flywheel would have to be brought backup to speed

Using formula of time

$t=\dfrac{46.88\times10^{6}}{11190}$

$t=4189.45\ sec$

$t=1.163\ hours$

Hence, (a). The kinetic energy stored in the fly wheel is 46.88 MJ.

(b). The time is 1.163 hours.

3 0

3 years ago

The points plotted on a graph represent the actual data recorded by an experiment.

aleksandr82 [10.1K]

True. Depending how accurate the graph is plotted

4 0

3 years ago

Read 2 more answers

Alexis is studying how lenses work. She looks through a

Kryger [21]

It would be the 3rd one

6 0

3 years ago

A wheel rotates with a constant angular acceleration of  rad/s2. During a certain time interval its angular displacement is  r

Hatshy [7]

Answer:

The angular velocity at the beginning of the interval is $\pi\sqrt{2}\ rad/s$ .

Explanation:

Given that,

Angular acceleration $\alpha=\pi\ rad/s^2$

Angular displacement $\theta=\pi\ rad$

Angular velocity $\omega =2\pi\ rad/s$

We need to calculate the angular velocity at the beginning

Using formula of angular velocity

$\alpha =\dfrac{\omega^2-\omega_{0}^2}{2\theta}$

$\omega_{0}^2=\omega^2-2\alpha\theta$

Where, $\alpha$ = angular acceleration

$\omega$ = angular velocity

Put the value into the formula

$\omega_{0}^2=(2\pi)^2-2\times\pi\times\pi$

$\omega=\sqrt{2\pi^2}$

$\omega_{0}=\pi\sqrt{2}\ rad/s$

Hence, The angular velocity at the beginning of the interval is $\pi\sqrt{2}\ rad/s$ .

3 0

3 years ago