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3 years ago

All types of exercise are appropriate at any age.

2 answers:

5 0

False.

This is false because some exercises can be too extreme for someone of old age, or young age. There are specifics types of exercise depending on your ability.

Anna11 [10]3 years ago

4 0

That is False, kids shouldn't pick up heavy weights

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What is the magnetic force on a 200 cm length of (straight) wire carrying a current of 30 A in a region where a uniform magnetic

Bezzdna [24]

Answer:

F = 0.112 N

Explanation:

To find the magnitude of magnetic force on the wire, you use the following formula:

$|\vec{F}|=|i\vec{L}\ X\ \vec{B}|=iLBsin\theta$ (1)

L: length of the wire = 200cm = 0.2m

i: current in the wire = 30 A

B: magnitude of the magnetic field = 0.055 T

θ: angle between the directions of L and B = 20°

You replace the values of L, i, B and θ in the equation (1):

$|\vec{F}|=(30A)(0.2m)(0.055T)sin(20\°)=0.112N$

hence, the magnetic force on teh wire is 0.112N

3 0

3 years ago

It takes Harry 34 s to walk from x1 = -11 m to x2 = -54 m .

miss Akunina [59]

Missing question:
"What is his velocity? Please answer using two sig figs in m/s."

Solution
The relationship between velocity (v), space (S) and time (t) is
 $v= \frac{S}{t}$
The space covered by Harry is
 $S=x_1 - x_2 = -11 m-(-54 m)=43 m$
and so the velocity is
 $v= \frac{43 m}{34 s} =1.26 m/s$

4 0

4 years ago

a pulley is used to lift a 2000 N safe over frosty's head. the safe is lifted 6m in 4s by Rudolph. how much power did Rudolph us

garri49 [273]

Answer:

3000W

Explanation:

Given parameter:

Weight of safe = 2000N

Height of lift = 6m

Time = 4s

Unknown:

Power used by Rudolph = ?

Solution:

Power is the rate at which work is being done. It is expressed as:

Power = $\frac{Work done }{Time taken}$

Work done = Weight x height = 2000 x 6 = 12000J

Power = $\frac{12000}{4}$ = 3000W

8 0

3 years ago

PV System for the Smith Family answers

Pavel [41]

System B: The amorphous silicon solar modules have an efficiency of 6%. The dimensions of the solar modules amount to 0.5m by 1.0m. The output of each module is 30 Wp. The modules cost 20€ each. The advanage of the amorphous silicon solar modules is that they perform better on cloudy days in which there is no direct sunlight. Installed in the Netherlands, this system gives, on a yearly basis, 10% more output per installed Wp than the multicrystalline silicon modules. 
System A: The efficiency of the multicrystalline silicon module amounts to 15%. The dimensions of the solar module are 0.5m by 1.0m. Each module has 75 Wp output. The modules cost 60€ each.

3 0

4 years ago

Determine the ratio β = v/c for each of the following.

nlexa [21]

Answer:

a) $\beta = 1.111\times 10^{-7}$ , b) $\beta = 9\times 10^{-7}$ , c) $\beta = 3.087\times 10^{-6}$ , d) $\beta = 2.5\times 10^{-5}$ , e) $\beta = 0.5$ , f) $\beta = 0.877$

Explanation:

From relativist physics we know that $c$ is the symbol for the speed of light, which equal to approximately 300000 kilometers per second. (300000000 meters per second).

a) A car traveling 120 kilometers per hour:

At first we convert the car speed into meters per second:

$v = \left(120\,\frac{km}{h} \right)\times \left(1000\,\frac{m}{km} \right)\times \left(\frac{1}{3600}\,\frac{h}{s} \right)$

$v = 33.333\,\frac{m}{s}$

The ratio $\beta$ is now calculated: ( $v = 33.333\,\frac{m}{s}$ , $c = 3\times 10^{8}\,\frac{m}{s}$ )

$\beta = \frac{33.333\,\frac{m}{s} }{3\times 10^{8}\,\frac{m}{s} }$

$\beta = 1.111\times 10^{-7}$

b) A commercial jet airliner traveling 270 meters per second:

The ratio $\beta$ is now calculated: ( $v = 270\,\frac{m}{s}$ , $c = 3\times 10^{8}\,\frac{m}{s}$ )

$\beta = \frac{270\,\frac{m}{s} }{3\times 10^{8}\,\frac{m}{s} }$

$\beta = 9\times 10^{-7}$

c) A supersonic airplane traveling Mach 2.7:

At first we get the speed of the supersonic airplane from Mach's formula:

$v = Ma\cdot v_{s}$

Where:

$Ma$ - Mach number, dimensionless.

$v_{s}$ - Speed of sound in air, measured in meters per second.

If we know that $Ma = 2.7$ and $v_{s} = 343\,\frac{m}{s}$ , then the speed of the supersonic airplane is:

$v = 2.7\cdot \left(343\,\frac{m}{s} \right)$

$v = 926.1\,\frac{m}{s}$

The ratio $\beta$ is now calculated: ( $v = 926.1\,\frac{m}{s}$ , $c = 3\times 10^{8}\,\frac{m}{s}$ )

$\beta = \frac{926.1\,\frac{m}{s} }{3\times 10^{8}\,\frac{m}{s} }$

$\beta = 3.087\times 10^{-6}$

d) The space shuttle, travelling 27000 kilometers per hour:

At first we convert the space shuttle speed into meters per second:

$v = \left(27000\,\frac{km}{h} \right)\times \left(1000\,\frac{m}{km} \right)\times \left(\frac{1}{3600}\,\frac{h}{s} \right)$

$v = 7500\,\frac{m}{s}$

The ratio $\beta$ is now calculated: ( $v = 7500\,\frac{m}{s}$ , $c = 3\times 10^{8}\,\frac{m}{s}$ )

$\beta = \frac{7500\,\frac{m}{s} }{3\times 10^{8}\,\frac{m}{s} }$

$\beta = 2.5\times 10^{-5}$

e) An electron traveling 30 centimeters in 2 nanoseconds:

If we assume that electron travels at constant velocity, then speed is obtained as follows:

$v = \frac{d}{t}$

Where:

$v$ - Speed, measured in meters per second.

$d$ - Travelled distance, measured in meters.

$t$ - Time, measured in seconds.

If we know that $d = 0.3\,m$ and $t = 2\times 10^{-9}\,s$ , then speed of the electron is:

$v = \frac{0.3\,m}{2\times 10^{-9}\,s}$

$v = 1.50\times 10^{8}\,\frac{m}{s}$

The ratio $\beta$ is now calculated: ( $v = 1.5\times 10^{8}\,\frac{m}{s}$ , $c = 3\times 10^{8}\,\frac{m}{s}$ )

$\beta = \frac{1.5\times 10^{8}\,\frac{m}{s} }{3\times 10^{8}\,\frac{m}{s} }$

$\beta = 0.5$

f) A proton traveling across a nucleus (10⁻¹⁴ meters) in 0.38 × 10⁻²² seconds:

If we assume that proton travels at constant velocity, then speed is obtained as follows:

$v = \frac{d}{t}$

Where:

$v$ - Speed, measured in meters per second.

$d$ - Travelled distance, measured in meters.

$t$ - Time, measured in seconds.

If we know that $d = 10^{-14}\,m$ and $t = 0.38\times 10^{-22}\,s$ , then speed of the electron is:

$v = \frac{10^{-14}\,m}{0.38\times 10^{-22}\,s}$

$v = 2.632\times 10^{8}\,\frac{m}{s}$

The ratio $\beta$ is now calculated: ( $v = 2.632\times 10^{8}\,\frac{m}{s}$ , $c = 3\times 10^{8}\,\frac{m}{s}$ )

$\beta = \frac{2.632\times 10^{8}\,\frac{m}{s} }{3\times 10^{8}\,\frac{m}{s} }$

$\beta = 0.877$

4 0

3 years ago