Two people are standing in the middle of a frozen pond that is frictionless. They want to move to the edges of the pond but are
1 answer:
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Answer:
v= 4.0 m/s
Explanation:
- When standing on the bathroom scale within the moving elevator, there are two forces acting on Henry's mass: Normal force and gravity.
- Gravity is always downward, and normal force is perpendicular to the surface on which the mass is located (the bathroom scale), in upward direction.
- Normal force, can adopt any value needed to match the acceleration of the mass, according to Newton's 2nd Law.
- Gravity (which we call weight near the Earth's surface) can be calculated as follows:
- According to Newton's 2nd Law, it must be met the following condition:
- As the gravity is larger than normal force, this means that the acceleration is downward, so, we choose this direction as the positive.
- Solving for a, we get:
- We can find the speed after the first 3.8 s (assuming a is constant), applying the definition of acceleration as the rate of change of velocity:
- Now, if during the next 3.8 s, normal force is 930 N (same as the weight), this means that both forces are equal each other, so net force is 0.
- According to Newton's 2nd Law, if net force is 0, the object is either or at rest, or moving at a constant speed.
- As the elevator was moving, the only choice is that it is moving at a constant speed, the same that it had when the scale was read for the first time, i.e., 4 m/s downward.
Answer:
(a)
(b)
(c)
Explanation:
Given that,
(a) An electron accelerated from rest through a potential difference of 100 V. The De Broglie wavelength in terms of potential difference is given by :
Where
m and e are the mass of and charge on an electron
On solving,
V = 100 V
(b) V = 1 kV = 1000 V
(c) If
Hence, this is the required solution.
According to the inverse square law of light, <span>apparent brightness will decrease by a factor of 9. Use the formula </span>
, to check it.