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timama [110]
2 years ago
4

A 40 kg box is placed on a 2 m tall shelf. a. What is the gravitational potential energy of the box? b. If the box falls off the

shelf, what is its kinetic energy as it strikes the ground? c. What is the velocity of the box immediately before it strikes the ground?
Physics
1 answer:
slamgirl [31]2 years ago
8 0

Answer:a) P.E= mgh

where m=40kg g=9.8m/s^2 h=2m

P.E=40×10×2

=800N

b)K.E=P.E

i.e, 1/2mv^2=mgh

1/2v^2=gh

where,g=9.8 h=2 v=?

1/2v^2=9.8×2

v^2=19.6×2

v^2=39.2

v=6.26m/s

therefore, K.E=1/2mv^

1/2×40×6.26^2

1/2×1567.5

K.E=783.8N

c) K.E=1/2mv^2

where, K.E=783.8N m=40kg v=?

783.8=1/2×40×v^2

783.8=20v^2

v^2=783.8/20

v^2=39.19

v=√39.19

v=6.26m/s^2

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Anna007 [38]

Explanation & answer:

Given:

Fuel consumption, C = 22 L/h

Specific gravity = 0.8

output power, P  =  55 kW

heating value, H = 44,000 kJ/kg

Solution:

Calculate energy intake

E = C*P*H

= (22 L/h) / (3600 s/h) * (1000 mL/L) * (0.8 g/mL) * (44000 kJ/kg)

= (22/3600)*1000*0.8*44000 j/s

= 215111.1 j/s

Calculate output power

P = 55 kW

= 55000 j/s

Efficiency

= output / input

= P/E

=55000 / 215111.1

= 0.2557

= 25.6% to 1 decimal place.

8 0
2 years ago
Light from a lamp is shining on a surface. how can you increase the intensity of the light on the surface?
vlada-n [284]
The intensity of a light in a surface follows the inverse square law formula which can be mathematically expressed as,
                         I = k/d²
where I is intensity, d is distance, and k is the proportionality constant. For us to increase the intensity, we should lower the distance from the source to the surface. 
4 0
2 years ago
Write a hypothesis about how the height of the cylinder affects the temperature of the water. Use the "if . . . then . . . becau
AnnyKZ [126]
The statement that can be used to answer this  question is:

"If the cylinder is brought higher then, its temperature when brought down becomes higher because a greater amount of potential energy is converted to thermal energy."

The potential energy is converted to thermal energy when the object is released the velocity becomes higher because of the acceleration due to gravity.
8 0
2 years ago
Read 2 more answers
In an attempt to impress its friends, an acrobatic beetle runs and jumps off the bottom step of a flight of stairs. The step is
Aleks04 [339]

Answer:

0.3677181864 m

Explanation:

u = Velocity = 1.5 m/s

\theta = Angle = 20°

y = -20 cm

Velocity components

u_x=ucos\theta\\\Rightarrow u_x=1.5cos20\\\Rightarrow u_x=1.40953\ m/s

u_y=usin\theta\\\Rightarrow u_y=1.5sin20\\\Rightarrow u_y=0.51303\ m/s

Acceleration components

a_x=0

a_y=-9.81\ m/s^2

y=u_yt+\dfrac{1}{2}a_yt^2\\\Rightarrow -0.2=0.51303\times t+\dfrac{1}{2}\times -9.81t^2\\\Rightarrow 4.905t^2-0.51303t-0.2=0

t=\frac{-\left(-0.51303\right)+\sqrt{\left(-0.51303\right)^2-4\cdot \:4.905\left(-0.2\right)}}{2\cdot \:4.905}, \frac{-\left(-0.51303\right)-\sqrt{\left(-0.51303\right)^2-4\cdot \:4.905\left(-0.2\right)}}{2\cdot \:4.905}\\\Rightarrow t=0.26088, -0.15629

Time taken is 0.26088 seconds

x=u_xt+\dfrac{1}{2}a_xt^2\\\Rightarrow x=1.40953\times 0.26088\\\Rightarrow x=0.3677181864\ m

The distance the beetle travels on the ground is 0.3677181864 m

6 0
2 years ago
A proton (1.6726 ? 10-27 kg) and a neutron (1.6749 ? 10-27 kg) at rest combine to form a deuteron, the nucleus of deuterium or "
Alexus [3.1K]

Answer:

Explanation:

The mass of the deuteron = mass of the proton + mass of the neutron + mass equivalent of the energy of 2.2 Mev evolved.

I amu = 931 Mev

2.2 Mev = 2.2 / 931 amu

= ( 2.2 / 931 )x 1.6726 x 10⁻²⁷

= .00395 x 10⁻²⁷

The mass of the deuteron  =( 1.6726 + 1.6749 +  .00395)x 10⁻²⁷ kg

= 3.35145 x 10⁻²⁷ kg

b ) Momentum of gamma ray

= h / λ ( h is plank's constant and λ is wavelength of gamma ray )

= hυ / υλ       (  υ is frequency of gamma ray )

= E / c  ( E is energy of photon and c is velocity o light )

= 2.2 x 10⁶ x 1.6 x 10⁻¹⁹  J / 3 x 10⁸

= 1.173 x 10⁻²¹ Kg m /s

This will be the momentum of deuteron also

Kinetic energy

= p² / 2m ( p is momentum and m is mass of deuteron )

= ( 1.173 x 10⁻²¹ )² / ( 2 x 3.35145 x 10⁻²⁷)

= 1.376 x ⁻¹⁵ J

Energy of gamma ray

= 2.2 x 10⁶ x 1.6 x 10⁻¹⁹  J

= 3.52 x 10⁻¹³ J

So kinetic energy of deuteron is smaller than energy of gamma ray photon .

5 0
2 years ago
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