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Gemiola [76]
3 years ago
10

A box of mass 26 kg is initially at rest on a flat floor. The coefficient of kinetic friction between the box and the floor is 0

.60. A woman pushes horizontally against the box with a force of 505 N until the box attains a speed of 2 m/s. What is the change in kinetic energy of the box?
Physics
1 answer:
Kazeer [188]3 years ago
3 0

Answer:

\Delta K = 52J

Explanation:

The change in kinetic energy will be simply the difference between the final and initial kinetic energies: \Delta K=K_f-K_i

We know that the formula for the kinetic energy for an object is:

K=\frac{mv^2}{2}

where <em>m </em>is the mass of the object and <em>v</em> its velocity.

For our case then we have:

\Delta K = K_f-K_i=\frac{mv_f^2}{2}-\frac{mv_i^2}{2}=\frac{m(v_f^2-v_i^2)}{2}

Which for our values is:

\Delta K = \frac{m(v_f^2-v_i^2)}{2} = \frac{(26Kg)((2m/s)^2-(0m/s)^2)}{2} = 52J

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Answer:

1°C

Explanation:

Water freezes at 0°C, 32°F, and 273°K.

The only temperature warmer than the freezing point is 1°C.

7 0
3 years ago
A projectile is shot horizontally at 23.4 m/s from the roof of a building 55.0 m tall. What is the time necessary for the projec
baherus [9]
The horizontal speed has no effect on the answer. 

It doesn't matter whether you flick a marble horizontally from the roof,
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Their vertical speed is completely determined by gravity, (and it happens to
be the same for all of them).

Handy dandy formula for the distance covered by anything that starts out
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            Distance = (1/2) (acceleration) x (time)²

If the beginning of the journey is on Earth, then the acceleration is
9.8 m/s² ... the acceleration of gravity on Earth.  We'll assume that
the 55-meter rooftop in the question is part of a building on Earth.

                       55 meters  =  (1/2) (9.8 m/s²) x (time)²           

Divide each side
by  4.9 m/s² :            55 m / 4.9 m/s²  =  (time)²

                                 (time)²  =  (55/4.9)  sec²

Square-root
each side:                time  =  √(55/4.9 sec²)

                                           =      3.35 sec  .
5 0
3 years ago
What type of properties would a scientist need to know to correctly place in new element into a group?
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Placing elements into columns, groups, rows and periods that share certain properties. properties such as gas, solid and liquid determine an element physical state at room temperature. 
3 0
3 years ago
Gravity on Jupiter is 25 m/s/s, what is the weight of a 12 kg object on Jupiter?
stiv31 [10]

Answer:

300 Newtons

Explanation:

Weight is the force of attraction between two bodies, one usually larger (like a planet), and one smaller (like a person). Force can be calculated using the formula: Force = mass × acceleration.

The mass here is 12kg, the acceleration, which in this case, is the acceleration due to gravity is 25m/s/s, by plugging in our values, we have

Force = 12 × 25 = 300 Newtons or 300 N for short.

3 0
2 years ago
Chapter 16, Problem 63. A person is standing in a room at 18 ◦C. The exposed surface area and skin temperature of the person are
Juliette [100K]

Answer:Q=248.011 W

Explanation:

Given

Temperature of Room T_{\infty }=18^{\circ}\approx 291 K

Area of Person A=1.7 m^2

Temperature of skin T=32^{\circ}\approx 305 K

Heat transfer coefficient h=5 W/m^2.k

Emissivity of the skin and clothes \epsilon =0.9

\Delta T=32-18=14^{\circ}

Total rate of heat transfer=heat Transfer due to Radiation +heat transfer through convection

Heat transfer due radiation Q_1=\epsilon \sigma A(T^4-T_{\infty }^4 )

where \sigma =stefan-boltzman\ constant

Q_1=0.9\times 5.687\times 10^{-8}\times 1.7\times (305^4-291^4)

Q_1=129.01 W

Heat Transfer due to convection is given by

Q_2=hA(\Delta T)

Q_2=5\times 1.7\times 14=119 W

Q=Q_1+Q_2

Q=129.01+119=248.011 W

7 0
3 years ago
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