A soccer ball was kicked . it had the mass of .42 kg and accelerated at 25m/s . what was the force?

A catapult’s lever holds a cannonball. The lever is attached to a tightly held rope. When the rope is released, the lever spring

vlada-n [284]

The answer is ELASTIC

6 0

3 years ago

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A square wire, 20 cm on the side, moves at constant speed parallel to the xy-plane into a region where there is a uniform magnet

Amanda [17]

Answer:

The speed of the wire is 5 m/s.

Explanation:

Given that,

Length = 20 cm

Magnetic field = 0.1 T

Current = 10 mA

Resistance $R= 10\Omega$

We need to calculate the speed of the wire

Using formula of emf

$\epsilon=Bvl$

Using formula of current

$I=\dfrac{\epsilon}{R}$

Put the value of $\epsilon$ into the formula of current

$I=\dfrac{Bvl}{R}$

$v=\dfrac{IR}{Bl}$

$v=\dfrac{10\times10^{-3}\times10}{0.1\times20\times10^{-2}}$

$v= 5\ m/s$

Hence, The speed of the wire is 5 m/s.

6 0

3 years ago

Suppose that the half-life of an element is 1000 years. How many half-lives will it take before one-eighth of the original sampl

34kurt

Answer:

3

Explanation:

The half-life of a radioactive isotope is the time it takes for the mass of the sample to halve.

This can be rewritten as follows:

$m(t) = m_0 (\frac{1}{2})^n$

where

m(t) is the mass of the sample at time t

m0 is the original mass of the sample

n is the number of half-lives that passed

We see that if we take n=3, the amount of original sample left is

$m(t) = m_0 (\frac{1}{2})^3 = m_0 (\frac{1}{8})$

So 3 (3 half-lives) is the correct answer.

3 0

3 years ago

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The speed of an electromagnetic wave traveling in a transparent nonmagnetic substance is v = 1/ κμ0ε0 , where κ is the dielectri

vladimir1956 [14]

Answer:

$v=2.24\times 10^{8}\ m/s$

Explanation:

Given that,

The speed of an electromagnetic wave traveling in a transparent nonmagnetic substance is given by :

$v=\dfrac{1}{\sqrt{k\mu_o\epsilon_o}}$

Where

k is the dielectric constant of the substance.

v is the speed of light in water

$c=\dfrac{1}{\sqrt{1.78\times 4\pi \times 10^{-7}\times 8.85\times 10^{-12}}}$

$v=2.24\times 10^{8}\ m/s$

So, the speed of light in water is $2.24\times 10^{8}\ m/s$

7 0

3 years ago

A small 20-kg canoe is floating downriver at a speed of 2 m/s. What is the canoe’s kinetic energy? A. 40 J B. 80 J C. 18 J

rusak2 [61]

A small 20-kg canoe is floating downriver at a speed of 2 m/s. 40 J is the canoe’s kinetic energy.

Answer: Option A

<u>Explanation:</u>

The given canoe has the mass and is being given to move at a speed. Therefore the kinetic energy of the canoe can be calculated using the following method,

Given that mass of the canoe = 20 kg and its speed =1 m/s

As we know that the Kinetic energy has the formula,

$\text {Kinetic energy}=\frac{1}{2} \boldsymbol{m} \boldsymbol{v}^{2}$

Therefore, substituting the value into the equation, we get,

$K . E .=\frac{1}{2} \times 20 \times 2^{2}$ = 40 J

4 0

3 years ago

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