How much work is done in lifting a 6 kg object from the ground to a height of 4m?

Which muscle group works the hardest (isometrically) when performing a wrist curl in the pronated position?

Elenna [48]

Hello!
I believe its A. wrist flexors but im not exactly sure because it might be B. wrist extensors.

6 0

3 years ago

The drawing shows a bicycle wheel resting against a small step whose height is h = 0.110 m. The weight and radius of the wheel a

Pavel [41]

Answer:

$F=27.39N$

Explanation:

Take sum of torques at the point the step touches the wheel, that eliminates two torques

Σ $T=T_{N}+T_{f}+T_{W}$

Since we are looking for when the wheel just starts to rise up N-> 0 so no torque due to normal force

$T_{N}=0$

The perpendicular lever arm for the F force is R-h

$T_{f}=F*(r-h)$

And the T of gravity according to the image

$T_{W}=W*(\sqrt{r^2-(r-h)^2}$

Σ $T=0$

$T_{N}+T_{f}+T_{W}=0$

$F*(r-h)+W*(\sqrt{r^2-(r-h)^2}=0$

$F=\frac{W*(\sqrt{r^2-(r-h)^2}}{r-h}$

$F=\frac{24.9 N*(\sqrt{0.336^2-(0.336-0.110)^2}}{(0.336-0.11)}$

$F=27.39N$

4 0

2 years ago

The electric potential at the dot in the figure is 3160 V. What is charge q?

PSYCHO15rus [73]

Hi there!

Recall the equation for electric potential of a point charge:

$V = \frac{kQ}{r}$

V = Electric potential (V)
k = Coulomb's Constant(Nm²/C²)

Q = Charge (C)
r = distance (m)

We can begin by solving for the given electric potentials. Remember, charge must be accounted for. Electric potential is also a SCALAR quantity.

Upper right charge's potential:

$V = \frac{(8.99*10^9)(-5 * 10^{-9})}{0.04} = -1123.75 V$

Lower left charge's potential:

$V = \frac{(8.99*10^9)(5*10^{-9})}{0.02} = 2247.5 V$

Add the two, and subtract from the total EP at the point:

$3160 + 1123.75 - 2247.5 = 2036.25$

The remaining charge must have a potential of 2036.25 V, so:

$2036.25 = \frac{(8.99*10^9)(Q)}{\sqrt{0.02^2 + 0.04^2}}\\\\2036.25 = \frac{(8.99*10^9)Q}{0.0447} \\\\Q = 0.000000010127 = \boxed{10.13nC}$

5 0

2 years ago

The amplitude, or magnitude, of a sinusoidal source is the maximum value of the source. What is the amplitude of the voltage sou

liraira [26]

Answer:

Explanation:

<u>Sinusoidal Functions</u>

A sinusoid or sinusoidal function is a sine or cosine which general equation is

$F(x)=A.sin(wt-\phi)$

Or also

$F(x)=A.cos(wt-\phi)$

Where A is the amplitude or maximum value, w is the angular frequency, t is the time and $\phi$ is the phase shift.

Comparing the given expression with the general formula

$v(t)=50cos(2000t-45^o) mV$

We can establish that A=50 mV = 0.05 V

$A = 0.05\ V$

7 0

3 years ago

A paper-filled capacitor is charged to a potential difference of V0=2.5 V. The dielectric constant of paper is k=3.7 . The capac

Pavlova-9 [17]

Answer:

k = 6.72

Explanation:

K of paper = 3.7

k of air = 1

Given that charge Q on the capacitor is constant because cell is disconnected from the circuit. So

V = Q / C = 2.5

Capacity becomes C / 3.7 in air .

capacity becomes C/3.7 when paper is replaced by air .

V₁ = Q / (C/3.7)

= 3.7 Q/C

3.7 x 2.5

= 9.25 V

In the second case ,

capacitance due to new unknown dielectric k

= C/3.7 x k

= kC / 3.7 ( Capacitance in air is C/3.7 )

V ( new ) = Q / ( kC/3.7 )

= 3.7 Q/kC

.55 x 2.5 = 3.7 x( 2.5 / k )

k = 3.7 / .55

= 6.72

7 0

2 years ago