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Mekhanik [1.2K]
3 years ago
13

When an athlete holds a barbell overhead, the reaction force is the weight of the barbell on his hand. how does this force vary

for the case where the barbell is decelerated upward?
Physics
1 answer:
Sonja [21]3 years ago
3 0
The force applied by the competitor is littler than the heaviness of the barbell. At the point when the barbell quickens upward, the power applied by the competitor is more prominent than the heaviness of the barbell. When it decelerates upward, the power applied by the competitor is littler than the heaviness of the barbell.
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Rosalind is an impulsive child who seldom waits for her turn when playing with other children. Rosalind's father is also an impu
wariber [46]

Answer:

Alburt Bandura

Explanation:

Rosalind has learned to be impulsive and seldom waits for her turn when playing with other children, this trait she has learned  from her father, who is also an impulsive man.

The theorist who would most likely suggest that Rosalind has learned to be impulsive from watching her father is Alburt Bandura. Alburt in his famous Bebo Doll experiment confirmed that children learn from the adults behavior in their life.

3 0
3 years ago
Un tubo cilindrico hueco de cobre mide 3 m de longitud tienen un diametro exterior de 4cm y un diametro interior de 2 cm¿cuanto
Irina-Kira [14]

Answer:

 W = 9.93 10² N

Explanation:

To solve this exercise we must use the concept of density

           ρ = m / V

the tabulated density of copper is rho = 8966 kg / m³

let's find the volume of the cylindrical tube

           V = A L

           V = π (R_ext  ² - R_int ²) L

let's calculate

          V = π (4² - 2²) 10⁻⁴  3

          V = 1.13 10⁻²  m³

         m = ρ V

        m = 8966 1.13 10⁻²

        m = 1.01 10² kg

the weight of the tube

        W = mg

         W = 1.01 10² 9.8

         W = 9.93 10² N

4 0
2 years ago
a 74.9 kg person sits at rest on an icy pond holding a physics book. he throws the physics book west at 8.25 m/s and he recoils
kifflom [539]

Answer:

1.95 kg

Explanation:

Momentum is conserved.

m₁ u₁ + m₂ u₂ = m₁ v₁ + m₂ v₂

0 = (74.9) (-0.215) + m (8.25)

m = 1.95

3 0
3 years ago
In February 1955, a paratrooper fell 370 m from an airplane without being able to open his chute but happened to land in snow, s
nevsk [136]

a) 0.94 m

The work done by the snow to decelerate the paratrooper is equal to the change in kinetic energy of the man:

W=\Delta K\\-F d = \frac{1}{2}mv^2 - \frac{1}{2}mu^2

where:

F=1.1 \cdot 10^5 N is the force applied by the snow

d is the displacement of the man in the snow, so it is the depth of the snow that stopped him

m = 68 kg is the man's mass

v = 0 is the final speed of the man

u = 55 m/s is the initial speed of the man (when it touches the ground)

and where the negative sign in the work is due to the fact that the force exerted by the snow on the man (upward) is opposite to the displacement of the man (downward)

Solving the equation for d, we find:

d=\frac{1}{2F}mu^2 = \frac{(68 kg)(55 m/s)^2}{2(1.1\cdot 10^5 N)}=0.94 m

b) -3740 kg m/s

The magnitude of the impulse exerted by the snow on the man is equal to the variation of momentum of the man:

I=\Delta p = m \Delta v

where

m = 68 kg is the mass of the man

\Delta v = 0-55 m/s = -55 m/s is the change in velocity of the man

Substituting,

I=(68 kg)(-55 m/s)=-3740 kg m/s

7 0
3 years ago
Find the emitted power per square meter of peak intensity for a 3000 k object that emits thermal radiation.
Aleksandr [31]
According to Stefan-Boltzmann Law, the thermal energy radiated by a radiator per second per unit area is proportional to the fourth power of the absolute temperature. It is given by;
    P/A = σ T⁴ j/m²s 
Where; P is the power, A is the area in square Meters, T is temperature in kelvin and σ is the Stefan-Boltzmann constant, ( 5.67 × 10^-8 watt/m²K⁴)
Therefore;
Power/square meter = (5.67 × 10^-8) × (3000)⁴
                                 =  4.59 × 10^6 Watts/square meter
8 0
3 years ago
Read 2 more answers
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