The speed of the runner is 300 m /38 seconds. You can simplify this answer to be about 7.9 m/s
Answer: work = 1,305kJ
Explanation:
angle= 30°
force= 1,500N
distance= 1,000m
The formula for work is : Work= force x distance, however there is an angle of 30° between the direction of force applied and the direction of motion, therefore force must be decomposed to its value on the horizontal axis which is the direction of motion by using the cosine of the very angle.
W= F×cos(α)×D
W= 1,500×cos (30)×1,000
W= 1,305kJ ( kilojoules)
Answer
D.Diffraction
Explanation
Diffraction is a property that is experienced by waves when they come across a barrier when they are in motion.
The ways tends to curve behind the barrier. This is called diffraction of waves.
Now, sound is a wave and it also experience diffraction. . So the brother will be able to hear the sound due to diffraction
Explanation:
It is given that,
Average power per unit mass generated by Lance, 
(a) Distance to cover race, 
Average speed of the person, v = 11 m/s
If t is the time taken to cover the race.
t = 14545.46 s
Let W is the work done. The relation between the work done and the power is given by :
W = 7090911.75 J
(b) Since, 
So, in 7090911.75 J, 
W = 1694.01 J
Hence, this is the required solution.
The answer is b. The crest.
Hope this helps!
