Answer:0.6kw
Explanation:
Power=force×velocity
Power=20×30=600w
In kw it's going to be 600/1000=0.6kw
That's false. Displacement would be (r2 - r1) .
Answer:
The percentage of its mechanical energy does the ball lose with each bounce is 23 %
Explanation:
Given data,
The tennis ball is released from the height, h = 4 m
After the third bounce it reaches height, h' = 183 cm
= 1.83 m
The total mechanical energy of the ball is equal to its maximum P.E
E = mgh
= 4 mg
At height h', the P.E becomes
E' = mgh'
= 1.83 mg
The percentage of change in energy the ball retains to its original energy,
ΔE % = 45 %
The ball retains only the 45% of its original energy after 3 bounces.
Therefore, the energy retains in each bounce is
∛ (0.45) = 0.77
The ball retains only the 77% of its original energy.
The energy lost to the floor is,
E = 100 - 77
= 23 %
Hence, the percentage of its mechanical energy does the ball lose with each bounce is 23 %
Answer:
The minimum time to get the car under max. speed limit of 79 km/h is 2.11 seconds.
Explanation:
![a=\frac{V_f-V_0}{t}](https://tex.z-dn.net/?f=a%3D%5Cfrac%7BV_f-V_0%7D%7Bt%7D)
isolating "t" from this equation:
![t=\frac{V_f-V_0}{a}](https://tex.z-dn.net/?f=t%3D%5Cfrac%7BV_f-V_0%7D%7Ba%7D)
Where:
a=
(negative because is decelerating)
![V_0= 114 km/h](https://tex.z-dn.net/?f=V_0%3D%20114%20km%2Fh)
First we must convert velocity from km/h to m/s to be consistent with units.
![79\frac{km}{h}*\frac{1000m}{1 km}*\frac{1h}{3600s}=\frac{79*1000}{3600}=21.94 m/s](https://tex.z-dn.net/?f=79%5Cfrac%7Bkm%7D%7Bh%7D%2A%5Cfrac%7B1000m%7D%7B1%20km%7D%2A%5Cfrac%7B1h%7D%7B3600s%7D%3D%5Cfrac%7B79%2A1000%7D%7B3600%7D%3D21.94%20m%2Fs)
![114\frac{km}{h}*\frac{1000m}{1 km}*\frac{1h}{3600s}=\frac{114*1000}{3600}=31.67 m/s](https://tex.z-dn.net/?f=114%5Cfrac%7Bkm%7D%7Bh%7D%2A%5Cfrac%7B1000m%7D%7B1%20km%7D%2A%5Cfrac%7B1h%7D%7B3600s%7D%3D%5Cfrac%7B114%2A1000%7D%7B3600%7D%3D31.67%20m%2Fs)
So;
![t=\frac{V_f-V_0}{a}=\frac{21.94 m/s-31.66m/s}{-4.6 m/s^2}=2.11 s](https://tex.z-dn.net/?f=t%3D%5Cfrac%7BV_f-V_0%7D%7Ba%7D%3D%5Cfrac%7B21.94%20m%2Fs-31.66m%2Fs%7D%7B-4.6%20m%2Fs%5E2%7D%3D2.11%20s)