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Andrei [34K]
3 years ago
14

Two friends are carrying a crate of mass 200 kg up a flight of stairs. The crate has length 1.25 m and height 0.500 m, and its c

enter of gravity is at its center. The stairs make a 45? angle with respect to the floor. The crate also is carried at an angle 45?, so that its bottom side is parallel to the slope of the stairs. The force each person applies is vertical.A) What is the magnitude of the upper person's force?B) What is the magnitude of the force applied by the bottom person?C) Is it best to be the person above or below on the stairs?
Physics
1 answer:
Marysya12 [62]3 years ago
4 0

Ans; see attached file for calculation and answer

Explanation:

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You place an ice cube of mass 7.50×10−3kg and temperature 0.00∘C on top of a copper cube of mass 0.220 kg. All of the ice melts,
g100num [7]

Answer:

T = 29.66 ^o C

Explanation:

As we know that here final equilibrium temperature is 0 degree C

so we can use energy conservation here

heat given by the cube = heat absorbed by the ice

so we have

ms \Delta T = m' L

so here we have

0.220(385)(T - 0) = (7.50 \times 10^{-3})(3.35 \times 10^5)

T = \frac{2512.5}{0.220 \times 385}

T = 29.66 ^o C

5 0
3 years ago
A single-turn square loop carries a current of 16 A . The loop is 15 cm on a side and has a mass of 3.8×10^−2kg . Initially the
DiKsa [7]

Answer:

The minimum magnetic field is 0.078 T.

Explanation:

Given that,

Current = 16 A

Side = 15 cm

Mass m= 3.8\times10^{-2}\ kg

Mass each segment in given square loop is

m=\dfrac{3.8\times10^{-2}}{4}

We need to calculate the torque due to gravity

Using formula of torque

\tau_{g}=2mg(\dfrac{L}{2})+mgL

\tau_{g}=2mgL

The torque due to magnetic field

\tau_{B}=FL

\tau_{B}=BIL^2

The equilibrium condition

\tau_{B}=\tau_{g}

Put the value into the formula

BIL^2=2mgL

B=\dfrac{2mgL}{IL^2}

B=\dfrac{2mg}{IL}

Put the value into the formula

B=\dfrac{2\times\dfrac{3.8\times10^{-2}}{4}\times9.8}{16\times15\times10^{-2}}

B=0.078\ T

Hence, The minimum magnetic field is 0.078 T.

7 0
3 years ago
Electrical energy is used to turn the blades of a fan. The amount of energy transformed is seen here : 750 J electrical energy i
Charra [1.4K]

Electrical energy is used to run the fan

Here as per given condition 750 J of electrical energy is used to run the fan which is converted into Kinetic energy as 400 J

So here we can see that 350 J of energy is lost against many other type of frictional and resistive loses.

So here we can say that out of 750 J of energy only 400 J is used to run the fan and rest amount of energy is lost against friction.

also we can say that efficiency of this fan will be

\eta = \frac{Useful}{Total}

\eta = \frac{400}{750}

\eta = \frac{8}{25}


3 0
2 years ago
Two factors that regulate (control) glandular secretion.
antiseptic1488 [7]

Answer:

The factors include age and puberty

Explanation:

Glandular secretion release chemicals such as hormones in response to the body’s metabolic needs.

As an individual ages , the metabolic rate of the body also reduces . This is due to the stress and ageing of the cells of the body. This explains why glandular secretion is optimal with young people and Lower in older people. It also explains why the immune system of a young person is mostly stronger than older people.

Puberty is another factor which affects glandular secretion as during puberty there is usually a high amount of hormonal changes due to high levels of secretions of some hormones. These hormones could however inhibit the other glandular secretions.

6 0
3 years ago
Suppose you designed a spacecraft to work by photon pressure. The sail was a completely absorbing fabric of area 1.0 km2 and you
Alekssandra [29.7K]

Answer:

(a) F = 6.14 *10⁻⁴ N

(b) P = 6.14* 10⁻¹⁰ Pa

(c) t = 27.2 min

Explanation:

Area of sail A = 1.0 km² = 1.0 * 10⁶m²

Wavelength of light  λ = 650 nm = 650 * 10⁻⁹ m

Rate of impact of photons R = 1 mol/s = 6.022 * 10²³ photons/s

(a)

Momentum of each photon is Ρ = h/λ = 6.625 * 10⁻³⁴ / 650 * 10⁻⁹

      = 1.0192 * 10⁻²⁷ kg.m/s

Since the photons are absorbed completely, in every collision the above momentum is transferred to the sail.  

Momentum transferred to the sail per second is product of rate of impact of photons and momentum transferred by each photon.

dp/dt = R * h/ λ

This is the force acting on the sail.

F = R * h/λ = 6.022 * 10²³ * 1.0192 * 10⁻²⁷ = 6.14 *10⁻⁴ N

F = 6.14 *10⁻⁴ N

b)

Pressure exerted by the radiation on the sail = Force acting on the sail / Area of the sail

P = F/A =  6.14 * 10⁻⁴ / 1.0 * 10⁶ =  6.14* 10⁻¹⁰ Pa

P = 6.14* 10⁻¹⁰ Pa

c)  

Acceleration of spacecraft a = F/m = 6.14 * 10⁻⁴ /1.0 = 6.14 * 10⁻⁴m/s²

As the spacecraft starts from rest, initial speed u=0,m/s ,

final speed is u = 1.0 m/s after time t  

v = u+at  

t = 1.0 - 0/ 6.14 * 10⁻⁴ =  1629s = 27.2 min

t = 27.2 min

4 0
3 years ago
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