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3 years ago

How fast must a 70 kg student be running to have a kinetic energy of 568 J?!

Physics

1 answer:

Dmitry [639]3 years ago

4 0

Answer: 4.03 m/s

Explanation: Kinetic energy is

KE = 1/2 m v²

So we derive the equation to have v.

v = √ 2KE / m

= 2 x 568 J / 70 kg

= 16.23

= √ 16.23

= 4.03 m/s

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A small toy car travels 2.0 meters in 120 seconds. what is the speed of the car?

mamaluj [8]

Answer: $\dfrac{1}{60} ms^{-1}$

Explanation:

Speed of an object is defined as the ratio of the distance covered by the object to the time taken to cover that distance.

Let $s$ be the speed of the object.

Let $D$ be the distance travelled by the object.

Let $t$ be the time taken by the object.

So, $s=\frac{D}{t}$

s= $\frac{2}{120}=\frac{1}{60}ms^{-1}$

So,the speed of the car is $\frac{1}{60}ms^{-1}$

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3 years ago

It's velocity changes, but its speed remains the same.<br> The<br> true or false

statuscvo [17]

Answer:

True

Explanation:

Velocity is a vector quantity, which means that it carries both magnitude and direction. Hence when direction of a particle changes, although magnitude (speed) may remain same, it's velocity changes due to direction change. For ex. A particle is m... A particle is moving along x axis with speed 1m/s, it's velocity will be represented as 1i (i represents unit vector along x)

But if it now starts moving along y axis, it's velocity is 1j (j represents unit vector along y axis). Hence velocity changes with direction.

brainllest pls .

7 0

3 years ago

Which statement accurately describes science?

slava [35]

Answer: We don’t really ever need to know how to dissect a frog but hey, one day maybe I’ll need to give a frog a discectomy

5 0

3 years ago

Is it possible to produce a continuous and oriented aramid fiber–epoxy matrix composite having longitudinalandtransverse moduli

Masja [62]

Answer:

Not possible

Explanation:

$E_{cl}$ = longitudinal modulus of elasticity = 35 Gpa

$E_{ct}$ = transverse modulus of elasticity = 5.17 Gpa

$E_m$ = Epoxy modulus of elasticity = 3.4 Gpa

$V_{\rho l}$ = Volume fraction of fibre (longitudinal)

$V_{\rho t}$ = Volume fraction of fibre (transvers)

$E_f$ = Modulus of elasticity of aramid fibers = 131 Gpa

Longitudinal modulus of elasticity is given by

$E_{cl}=E_m(1-V_{\rho l})+E_fV_{\rho l}\\\Rightarrow 35=3.4(1-V_{\rho l})+131V_{\rho l}\\\Rightarrow 35=3.4-3.4V_{\rho l}+131V_{\rho l}\\\Rightarrow V_{\rho l}=\frac{35-3.4}{131-3.4}\\\Rightarrow V_{\rho l}=0.24764$

Transverse modulus of elasticity is given by

$E_{ct}=\frac{E_mE_f}{(1-V_{\rho t})E_f+V_{\rho t}E_m}\\\Rightarrow 5.17=\frac{3.4\times 131}{(1-V_{\rho t})131+V_{\rho t}3.4}\\\Rightarrow \frac{3.4\times 131}{5.17}-131=-127.6V_{\rho t}\\\Rightarrow V_{\rho t}=\frac{\frac{3.4\times 131}{5.17}-131}{-127.6}\\\Rightarrow V_{\rho t}=0.35148$

$V_{\rho l}\neq V_{\rho t}$

Hence, it is not possible to produce a continuous and oriented aramid fiber.

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3 years ago

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katen-ka-za [31]

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3 years ago

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