1 A car travels 600 m in 30 s. What is its average speed?
2 answers:
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Answer:
1) f= 8.6 GHz
2) t= 0.2 ms
Explanation:
1)
- Since microwaves are electromagnetic waves, they move at the same speed as the light in vacuum, i.e. 3*10⁸ m/s.
- There exists a fixed relationship between the frequency (f) , the wavelength (λ) and the propagation speed in any wave, as follows:
- Replacing by the givens, and solving for f, we get:
⇒ f = 8.6 Ghz (with two significative figures)
2)
- Assuming that the microwaves travel at a constant speed in a straight line (behaving like rays) , we can apply the definition of average velocity, as follows:
where v= c= speed of light in vacuum = 3*10⁸ m/s
d= distance between mountaintops = 52 km = 52*10³ m
- Solving for t, we get:
⇒ t = 0.2 ms (with two significative figures)
Answer:
The mass of object is calculated as 5.36 kg
Explanation:
The known terms to find the mass are:
acceleration of object (a) = 22.35
Force exerted (F) = 120N
mass of an object (m) = ?
From Newton's second law of motion;
F = ma
or, 120 = m × 22.35
or, m= kg
∴ m = 5.36 kg
Missing questions: "find the speed of the electron".
Solution:
the magnetic force experienced by a charged particle in a magnetic field is given by
where
q is the particle charge
v its velocity
B the magnitude of the magnetic field
the angle between the directions of v and B.
Re-arranging the formula, we find:
and by substituting the data of the problem (the charge of the electron is
), we find the velocity of the electron:
Solution:
the magnetic force experienced by a charged particle in a magnetic field is given by
where
q is the particle charge
v its velocity
B the magnitude of the magnetic field
Re-arranging the formula, we find:
and by substituting the data of the problem (the charge of the electron is