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Phantasy [73]
3 years ago
15

A force that needs to touch something to affect it

Physics
2 answers:
bija089 [108]3 years ago
8 0


I would say friction because it requires to surfaces in order for the force to take place

correct me if I'm wrong.

Levart [38]3 years ago
4 0
Our life is full of forces. We cannot see these forces but we can see how they affect different things
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If we mechanically expand a gas into a larger volume, while keeping the temperature constant, what happens to the pressure?
bezimeni [28]
C. The pressure decreases, and we can precisely predict by how much.
4 0
3 years ago
The concrete sections of a certain superhighway are designed to have a length of 23.0 m. The sections are poured and cured at 10
loris [4]

Answer:

0.88 cm

Explanation:

Initial length at 10°c, L = 23 m

Rise of temperature, Δt = 42 - 10 = 32°c

Coefficient of linear expansion of concrete, α = 12 x 10^(-6) per°c

Minimum spacing to be left = α L Δt

=12\times10^{-6}\times23\times32

=8.832\times10^{-3}m

= 8.832 x 10^{-1} cm

= 0.88 cm

Note: I have a chosen a general value of 12 x 10^-6 per deg c for coefficient of expansion of  concrete. However, please refer to the value given in your text book and substitute it for an accurate answer.

8 0
3 years ago
A skater goes into a spin with her arms pulled in (close to her body). When she stretches her arms out: A) her angular speed ω d
musickatia [10]

Answer:

When she stretches her arms out,<em> B) her angular speed ω increases due to her moment of inertia decreasing</em>

Explanation:

The angular momentum of a rotating object is defined as the product of its moment of inertia and angular speed.

<em>L = I ω</em>

<em>where</em>

  • <em>L is the angular momentum</em>
  • <em>I is the moment of inertia</em>
  • <em>ω is the angular speed</em>

<em />

According to the principle of conservation of angular momentum, if there is no external torque, angular momentum of the skater must remain conserved. If the initial and final moment of inertia is <em>I_i and I_f  </em>while corresponding angular velocities are <em>ω_i and ω_f , </em>then the principle of conservation of angular momentum can be expressed as the following equation:

<em>(I_f) (ω_f) = (I_i) (ω_i)</em>

<em>ω_f / ω_i = I_i / I_f</em>

<em />

From the expression above, we can see that if the moment of inertia decreases, angular velocity would increase to conserve angular momentum of the skater.

Therefore, When she stretches her arms out,<em> her angular speed ω increases due to her moment of inertia decreasing.</em>

5 0
4 years ago
A water wave traves with a length of 10 meters and a frequency of 30 hertz, what is the velocity of the wave?
UNO [17]

Answer: 300 m/s

Explanation:

Given that:

length of water wave (λ) = 10 metres

Frequency of water wave (F) = 30 Hertz

Velocity of water wave (V) = ?

The velocity of a wave is the distance covered by the wave in one second. It is measured in metre per second, and represented by the symbol V. It is related to frequency and wave length by the formula: V = F λ

V = 30 Hertz x 10 metres

V = 300 m/s

Thus, the velocity of the water wave is 300 m/s

4 0
3 years ago
As a stunt for movie two cars are to collide with each other head on. The two cars are initially 125 apart. Car A is heading str
Tema [17]

Answer:

3.39724 seconds

23.0824792352 m, 101.917520765 m

13.58896 m/s

Explanation:

t = Time taken

u = Initial velocity

v = Final velocity

s = Displacement

a = Acceleration

The equation of motion will be

s=ut+\dfrac{1}{2}at^2\\\Rightarrow 125=30\times t+\dfrac{1}{2}\times 4\times t^2\\\Rightarrow 2t^2+30t-125=0\ m

t=\frac{5\left(\sqrt{19}-3\right)}{2},\:t=-\frac{5\left(3+\sqrt{19}\right)}{2}\\\Rightarrow t=3.39724, -18.39724

The time at which the cars collide is 3.39724 seconds

s=ut+\dfrac{1}{2}at^2\\\Rightarrow s=0\times t+\dfrac{1}{2}\times 4\times 3.39724^2\\\Rightarrow s=23.0824792352\ m

Car B traveled 23.0824792352 m and Car A traveled 125-23.0824792352 = 101.917520765 m

v=u+at\\\Rightarrow v=0+4\times 3.39724\\\Rightarrow v=13.58896\ m/s

The speed of car B is 13.58896 m/s

4 0
3 years ago
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