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3 years ago

5

/How much kinetic energy does an 80 kg man have while running at 1.5 m/s

1 answer:

igomit [66]3 years ago

7 0

K.E = 0.5 * m * v^2
= 0.5 * 80 * (1.5)^2
K.E = 90 joule

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You have been hired to design a spring-launched roller coaster that will carry two passengers per car. The car goes up a 12-m-hi

Vlada [557]

Answer:

Vmax=11.53 m/s

Explanation:

from conservation of energy

$E_A} =E_{B}$

Spring potential energy =potential energy due to elevation

0.5*k*x²= mg $(h_{B}-h_{A} )$ =mgh

0.5*k*2.3²= 430*9.81*6

k=9568.92 N/m

For safety reason

k"=1.13 *k= 1.13*9568.92

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agsin from conservation of energy

$E_A} =E_{C}$

spring potential energy=change in kinetic energy

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4 years ago

Two insulated copper wires of similar overall diameter have very different interiors. One wire possesses a solid core of copper,

balandron [24]

Answer with Explanation:

We are given that

Radius of solid core wire=r=2.28 mm= $2.28\times 10^{-3} m$

$1mm=10^{-3} m$

Radius of each strand of thin wire=r'=0.456 mm= $0.456\times 10^{-3} m$

Current density of each wire= $J=3750 A/m^2$

a.Area = $\pi r^2$

Where $\pi=3.14$

Using the formula

Cross section area of copper wire has solid core = $3.14\times (2.28\times 10^{-3})^2=16.3\times 10^{-6} m^2$

Current density = $J=\frac{I}{A}$

Using the formula

$3750=\frac{I}{16.3\times 10^{-6}}$

$I=3750\times 16.3\times 10^{-6}=0.061 A$

Total number of strands=19

Area of strand wire= $A'=19\times 3.14\times (0.456\times 10^{-3})^2=12.4\times 10^{-6} m^2$

$J'=\frac{I'}{A'}$

$3750=\frac{I'}{19\times 3.14(0.456\times 10^{-3})^2}$

$I'=3750\times 19\times 3.14(0.456\times 10^{-3})^2$

$I'=0.047 A$

b.Resistivity of copper wire= $\rho=1.69\times 10^{-8}\Omega-m$

Length of each wire =6.25 m

Resistance, R= $\frac{\rho l}{A}$

Using the formula

Resistance of solid core wire= $R=\frac{1.69\times 10^{-8}\times 6.25}{16.3\times 10^{-6}}=6.5\times 10^{-3}\Omega$

Resistance of strand wire= $R'=\frac{1.69\times 10^{-8}\times 6.25}{12.4\times 10^{-6}}=8.5\times 10^{-3}\Omega$

7 0

3 years ago

7. A runner runs on the track field with a velocity of 20 m/s and it is known that her momentum is

Dennis_Churaev [7]

Answer:

Weight of the runner is 60 kilograms

Explanation:

Momentum is the product of weight and velocity.

The formula is : p=mv where m is mass in kg and v is velocity in m/s

Given in the question ;

v= 20 m/s and p=1200 kg*m/s

Applying the formula as;

p= mv

1200 = m * 20

1200/20 = m

60 kg = m

4 0

3 years ago