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2 years ago

5

The total power input to the LED was 0.24 W.

1 answer:

just olya [345]2 years ago

4 0

Answer: How do you calculate useful power output?

Explanation: Hence, useful energy output:

Wuseful=F×d=10×5=50 J W useful = F × d = 10 × 5 = 50 J. ...

Ewasted=65−50=15 J E wasted = 65 − 50 = 15 J. ...

Efficiency=Useful energy outputTotal energy input×100%=5065×100%=76.9% Efficiency = Useful energy output Total energy input × 100 % = 50 65 × 100 % = 76.9 %

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The alarm at a fire station rings and a 87.5-kg fireman, starting from rest, slides down a pole to the floor below (a distance o

blsea [12.9K]

Answer:

$F_f=840N$

Explanation:

From the question we are told that

Weight of fireman $W_f= 87.5kg$

Pole distance $D=4.10m$

Final speed is $V_f 1.75m/s$

Generally the equation for velocity is mathematically represented as

$v^2 = v_0^2 + 2 a d$

Therefore Acceleration a

$a'= v^2 / 2 d$

$a'= 0.21m/s^2$

Generally the equation for Frictional force $F_f$ is mathematically given as

$F_f=m*a$

$F_f=m*(g-0.21)$

$F_f=87.5*(9.81-0.21)$

Therefore

$F_f=840N$

6 0

3 years ago

Which of the following elements are least abundant in the solar system?

Art [367]

The answer to this question is Helium

7 0

2 years ago

A stone is thrown with an initial speed of 11.5 m/s at an angle of 50.0 above the horizontal from the top of a 30.0-m-tall build

rewona [7]

Answer:

The magnitude of the horizontal displacement of the rock is 7.39 m/s.

Explanation:

Given that,

Initial speed = 11.5 m/s

Angle = 50.0

Height = 30.0 m

We need to calculate the horizontal displacement of the rock

Using formula of horizontal component

$v_{x}=u\cos\theta$

Put the value into the formula

$v_{x}=11.5\times\cos50$

$v_{x}=7.39\ m/s$

Hence, The magnitude of the horizontal displacement of the rock is 7.39 m/s.

8 0

3 years ago

A ball of mass m falls vertically, hits the floor with a speed ui , and rebounds with a speed u f . what is the magnitude of the

Sholpan [36]

Answer:

Change of momentum = M (Vf - (-Vi)) where V represents the scalar speeds of the ball or

I = M (ui + uf) and I is the impulse ΔM V = I Force = Change in Momentum

5 0

1 year ago

When beryllium-7 ions (m = 11.65 × 10-27 kg) pass through a mass spectrometer, a uniform magnetic field of 0.205 T curves their

AysviL [449]

Answer:

ratio =0.3075 T

Explanation:

The magnetic field B creates a force on a moving charge such that

$F = qvB$

Now this causes a centripetal acceleration

$F = = mv^2/r$

so

$qvB = mv^2/r$ ...........(i)

$B = mv/(rq)$ ...............(ii)

If accelerating potential V is same and then kinetic energy equals the potential energy difference

$\frac{1}{2} mv^2 = Vq$

$v = \sqrt{(2Vq/m)}$ put these value in equation (ii)

$B = m\frac{\sqrt{(2Vq/m)} }{rq}$

simplifying we get

$B =m \frac{(\sqrt{ 2Vm/q})}{r}$

for same location r will be same in both case

$B_{7} = \frac{ \sqrt{(m_{7})(2V/q) }}{r}$ ..............(iii)

$B_{10} = \frac{ \sqrt{(m_{10})(2V/q) }}{r}$ ..........(iv)

dividing (iv) and (iii) equation we get

$\frac{B_{10}}{B_{7}} = \sqrt{\frac{m_{10}}{{m_7}} }$

${B_{10}} = B_{7} \sqrt{\frac{m_{10}}{{m_7}} }$

$B_{10} = 0.2574T\sqrt{\frac{ (1.663x10^-26}{(1.165x10^-26)}$

so on solving we get

=0.3075 T

5 0

3 years ago