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PtichkaEL [24]
4 years ago
14

A truck accidentally rolls down a driveway for 8.0\,\text m8.0m8, point, 0, start text, m, end text while a person pushes agains

t the truck with a force of 850\,\text N850N850, start text, N, end text to bring it to a stop. What is the change in kinetic energy for the truck?
Physics
1 answer:
gavmur [86]4 years ago
5 0

Answer:

Explanation:

According to work energy theorem

change in kinetic energy of truck = work done against it

work done against it = force x displacement

= - 850 x 8 = 6800 J

change in kinetic energy of truck = - 6800 J .

energy will be reduced by 6800 J

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A vertical, solid steel post 25 cm in diameter and 2.50m long is required to support a load of 8000kg. You can ignore the weight
Gwar [14]

(a) The stress in the post is 1,568,000 N/m²

(b) The strain in the post is  7.61 x 10⁻⁶  

(c) The change in the post’s length when the load is applied is 1.9 x 10⁻⁵ m.

<h3>Area of the steel post</h3>

A = πd²/4

where;

d is the diameter

A = π(0.25²)/4 = 0.05 m²

<h3>Stress on the steel post</h3>

σ = F/A

σ = mg/A

where;

  • m is mass supported by the steel
  • g is acceleration due to gravity
  • A is the area of the steel post

σ = (8000 x 9.8)/(0.05)

σ = 1,568,000 N/m²

<h3>Strain of the post</h3>

E = stress / strain

where;

  • E is Young's modulus of steel = 206 Gpa

strain = stress/E

strain = (1,568,000) / (206 x 10⁹)

strain = 7.61 x 10⁻⁶

<h3>Change in length of the steel post</h3>

strain = ΔL/L

where;

  • ΔL is change in length
  • L is original length

ΔL = 7.61 x 10⁻⁶ x 2.5

ΔL = 1.9 x 10⁻⁵ m

Learn more about Young's modulus of steel here: brainly.com/question/14772333

#SPJ1

7 0
2 years ago
Would it be better to collide head-on with an identical car traveling at the same speed or collide with a stationary brick wall?
attashe74 [19]
It makes no difference. The momentum of either car goes to zero in both cases.
6 0
3 years ago
Superman is supposed to leap tall buildings in a single bound. Suppose that he obeys the normal laws of physics in this feat. Es
lys-0071 [83]

Answer:

31.32 m/s

Explanation:

t = Time taken

u = Initial velocity

v = Final velocity

s = Displacement

a = Acceleration due to gravity = 9.81 m/s²

Let us assume the height of the Disque hall is 50 m

v^2-u^2=2as\\\Rightarrow -u^2=2as-v^2\\\Rightarrow u=\sqrt{v^2-2as}\\\Rightarrow u=\sqrt{0^2-2\times -9.81\times 50}\\\Rightarrow u=31.32\ m/s

In order to make the jump Superman's initial velocity must be greater than or equal to 31.32 m/s

6 0
3 years ago
A beam of monochromatic light with a wavelength of 400 nm in air travels into water. what is the wavelength of the light in wate
slava [35]
The refractive index of water is n=1.33. This means that the speed of the light in the water is:
v= \frac{c}{n}= \frac{3 \cdot 10^8 m/s}{1.33 }=2.26 \cdot 10^8 m/s

The relationship between frequency f and wavelength \lambda of a wave is given by:
\lambda= \frac{v}{f}
where v is the speed of the wave in the medium. The frequency of the light does not change when it moves from one medium to the other one, so we can compute the ratio between the wavelength of the light in water \lambda_w to that in air \lambda as
\frac{\lambda_w}{\lambda}= \frac{ \frac{v}{f} }{ \frac{c}{f} } = \frac{v}{c}
where v is the speed of light in water and c is the speed of light in air. Re-arranging this formula and by using \lambda=400 nm, we find
\lambda_w = \lambda \frac{v}{c}=(400 nm) \frac{2.26 \cdot 10^8 m/s}{3 \cdot 10^8 m/s}=301 nm
which is the wavelength of light in water.
5 0
3 years ago
A 15 W electric shaver is used for 3 minutes. How much energy does it use in joules?​
borishaifa [10]
P=change in E/t
Change in E=p*t
=15*3
=45

The answer is 45J.
3 0
3 years ago
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