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BaLLatris [955]
3 years ago
12

n a downhill ski race, surprisingly, little advantage is gained by getting a running start. (This is because the initial kinetic

energy is small compared with the gain in gravitational potential energy on even small hills.) To demonstrate this, find the final speed and the time taken for a skier who skies 70.0 m along a 30â slope neglecting friction: (a) Starting from rest. (b) Starting with an initial speed of 2.50 m/s. (c) Does the answer surprise you? Discuss why it is still advantageous to get a running start in very competitive events.
Physics
1 answer:
Annette [7]3 years ago
7 0

Answer:

Explanation:

a ) starting from rest , so u = o and initial kinetic energy = 0 .

Let mass of the skier = m

Kinetic energy gained = potential energy lost

= mgh = mg l sinθ

= m x 9.8 x 70 x sin 30

= 343 m

Total kinetic energy at the base = 343 m  + 0 = 343 m .

b )

In this case initial kinetic energy = 1/2 m v²

= .5 x m x 2.5²

= 3.125 m

Total kinetic energy at the base

= 3.125 m  + 343 m

= 346.125 m

c ) It is not surprising as energy gained due to gravitational force by the earth is enormous . So component of energy gained due to gravitational force far exceeds the initial kinetic energy . Still in a competitive event , the fractional initial kinetic energy may be the deciding factor .

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What is the temperature of a sample of gas when the average translational kinetic energy of a molecule in the sample is 8.37 × 1
-BARSIC- [3]

Answer:

404K

Explanation:

Data given, Kinetic Energy.K.E=8.37*10^-21J

Note: as the temperature of a is increase, the rate of random movement will increase, hence leading to more collision per unit time. Hence we can say that the relationship between the kinetic energy and the temperature is a direct variation.

This relationship can be expressed as

K.E=\frac{3}{2}KT

where K is a constant of value 1.38*10^-23

Hence if we substitute the values, we arrive at

T=\frac{2/3(8.37*10^{-21})}{1.38*10^-23}\\ T=404K

converting to degree we have 131^{0}C

4 0
3 years ago
What is a combination of two or more simple machines?
Anna [14]

A compound

Explanation:

A compound machine is the combination of two or more simple machines.

An example is bicycle.

  • A simple machine is a device that is used to increase the magnitude of force.
  • It is a basic mechanical unit.
  • Examples are inclined planes, lever systems, wheel and axle.
  • A compound machine is a combination of these simple machines.

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7 0
3 years ago
A 3.06kg stone is dropped from a height of 10.0m and strikes the ground with a velocity of 7.00m/s. What average force of air fr
xxTIMURxx [149]
<span>22.5 newtons. First, let's determine how much energy the stone had at the moment of impact. Kinetic energy is expressed as: E = 0.5mv^2 where E = Energy m = mass v = velocity Substituting known values and solving gives: E = 0.5 3.06 kg (7 m/s)^2 E = 1.53 kg 49 m^2/s^2 E = 74.97 kg*m^2/s^2 Now ignoring air resistance, how much energy should the rock have had? We have a 3.06 kg moving over a distance of 10.0 m under a force of 9.8 m/s^2. So 3.06 kg * 10.0 m * 9.8 m/s^2 = 299.88 kg*m^2/s^2 So without air friction, we would have had 299.88 Joules of energy, but due to air friction we only have 74.97 Joules. The loss of energy is 299.88 J - 74.97 J = 224.91 J So we can claim that 224.91 Joules of work was performed over a distance of 10 meters. So let's do the division. 224.91 J / 10 m = 224.91 kg*m^2/s^2 / 10 m = 22.491 kg*m/s^2 = 22.491 N Rounding to 3 significant figures gives an average force of 22.5 newtons.</span>
3 0
3 years ago
I will give u brainliest
irakobra [83]

Answer:

the answer choices are at the bottom right?

Explanation:

5 0
3 years ago
A tiny particle with charge + 5.0 μC is initially moving at 55 m/s. It is then accelerated through a potential difference of 500
Vadim26 [7]

Answer:

ΔK.E = 2.5 × 10⁻³ J

Explanation:

Given data in the question, we have:

Charge of the particle, q = 5.0 μC = 5 × 10 ⁻⁶ C

Initial speed of the particle, v = 55 m/s

The potential difference, ΔV = 500 V

Now, the gain in kinetic energy is given as

ΔK.E = q × ΔV

on substituting the values in the above formula, we get

ΔK.E = 5 × 10 ⁻⁶ C × 500 V

or

ΔK.E = 2.5 × 10⁻³ J

8 0
3 years ago
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