Physics teacher guide grade 9
1 answer:
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Answer:
C) 0.00026 Hz
Explanation:
- In any wave, there exists a fixed relationship between the speed v, the frequency f and the wavelength λ, as follows:
- Replacing by the givens in (1), and solving for f, we get:
- Converting the units to Hz (1/sec), we get:
- The answer C. is the right one.
The average force is -2600 N
Explanation:
First of all, we need to calculate the acceleration of the man during the collision, which is given by the suvat equation:
where:
v = 0 is his final velocity (he comes to a stop)
u = 4.0 m/s is the initial velocity
a is the acceleration
s = 0.20 m is the distance covered
Solving for a,
The negative sign indicates that it is a deceleration.
Now we can find the average force on the man by using Newton's second law of motion:
where
m = 65 kg is the mass
And substituting,
where the negative sign indicates the force is in the direction opposite to the motion.
Learn more about force and Newton's second law:
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