The speed after 21 s is 18.9 m/s and the total time required for the train to reach a speed of 34 m/s is 14.4 s
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What is Speed ?</h3>
Speed is a distance travelled by a body per time taken. It is a scalar quantity and it is measured in m/s
Given that at Initially stationary, a train has a constant acceleration of 0.9 m/s2.
(a) What is its speed after 21 s?
- Acceleration a = 0.9 m/s²
Using v = u + at
Substitute all the parameters into the equation
v = 0 + 0.9 x 21
v = 18.9 m/s
(b) What is the total time required for the train to reach a speed of 34 m/s?
Let first calculate for total distance by using
v² = u² + 2as
34² = 18.9² + 2 × 0.9 × S
1156 = 357.21 + 1.8S
1.8S = 1156 - 357.21
1.8S = 798.79
S = 798.79 / 1.8
S = 443.8 m/s
v = u + at
34 = 21 + 0.9t
0.9t = 34 - 21
0.9t = 13
t = 13/0.9
t = 14.44s
Therefore, its speed after 21 s is 18.9 m/s and the total time required for the train to reach a speed of 34 m/s is 14.4 s
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Ep = mgh = 47.0 J
m = 0.8 kg
g = 9.81 m/s2 (average)
h = Ep / mg = 47 J / 0.8 kg * 9.81 m/s2 = 5.989 m
Answer:
The angular magnification is
Explanation:
From the question we are told
The focal length is
The near point is
The angular magnification is mathematically represented as
Substituting values
The answer is ; white dwarfs are warmer and have lower luminosity than supergiants
The reason white dwarfs have lower luminosity is that they are way smaller in size than supergiants, even though their temperatures are way higher in comparison.
White dwarfs and red giants are formed when the hydrogen fuel at the core of the stars is exhausted. When the star is 1 to 10 solar masses of the sun, then it forms a red giant.
Without friction, Newton's second law, in the form F=ma would apply.100=50a. So the acceleration should be 2m/s^2100-friction = 50x1.5100-friction = 75100-75=friction25N = friction