The speed of the train is 72 kilometers per hour find its speed in meters per second

Sarah, whose mass is 40 kg, is on her way to school after a winter storm when she accidentally slips on a patch of ice whose coe

RideAnS [48]

Sarah's acceleration is $-0.49 m/s^2$

Explanation:

The force of kinetic friction acting on Sarah has a magnitude which is given by:

$F_f = \mu mg$

where

$\mu$ is the coefficient of kinetic friction

m is Sarah's mass

g is the acceleration of gravity

Moreover, according to Newton's second law of motion, we know that the net force on Sarah is equal to its mass times its acceleration:

$F=ma$

where a is the acceleration

Since the force of friction is the only force acting on Sarah, we can say that the net force is equal to the force of friction, therefore:

$F=-\mu mg = ma$

where the negative sign is due to the fact that the force of friction has a direction opposite to the motion of Sarah. Solving for a, we find

$a=-\mu g$

And substituting the following values:

$\mu = 0.05$ (coefficient of friction)

$g=9.81 m/s^2$ (acceleration of gravity)

we find:

$a=-(0.05)(9.81)=-0.49 m/s^2$

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4 0

3 years ago

Please please help I'm stuck!!!

Korvikt [17]

Answer: iDc im in 3grade

Explanation:sorry

6 0

3 years ago

Read 2 more answers

Atoms of two different elements must have different

sergejj [24]

Explanation:

C. Atomic numbers....

4 0

3 years ago

one of the lady spartans was falling to the ground after dunking the winning basket. At the end of her fall, she was falling 4 m

Tresset [83]

Answer:

15 is the correct answer I.t.

8 0

3 years ago

What fraction of all the electrons in a 25 mg water

mihalych1998 [28]

Answer:

$9.11\times 10^{-15}.$

Explanation:

The water droplet is initially neutral, it will obtain a 40 nC of charge when a charge of -40 nC is removed from the water droplet.

The charge on one electron, $\rm e=-1.6\times 10^{-19}\ C.$

Let the N number of electrons have charge -40 nC, such that,

$\rm Ne=-40\ nC\\\Rightarrow N=\dfrac{-40\ nC}{e}=\dfrac{-40\times 10^{-9}\ C}{-1.6\times 10^{-19}\ C}=2.5\times 10^{11}.$

Now, mass of one electron = $\rm 9.11\times 10^{-31}\ kg.$

Therefore, mass of N electrons = $\rm N\times 9.11\times 10^{-31}=2.5\times 10^{11}\times 9.11\times 10^{-31}=2.2775\times 10^{-19}\ kg.$

It is the mass of the of the water droplet that must be removed in order to obtain a charge of 40 nC.

Let it is m times the total mass of the droplet which is $25\ \rm mg = 25\times 10^{-6}\ kg.$

Then,

$\rm m\times (25\times 10^{-3}\ kg) = 2.2775\times 10^{-19}\ kg.\\m=\dfrac{2.2775\times 10^{-19}\ kg}{25\times 10^{-3}\ kg}=9.11\times 10^{-15}.$

It is the required fraction of mass of the droplet.

3 0

3 years ago