Some work will be done on friction between wheels and road but it is negligible compared to work done on friction on breaks.
W = Ek = (m*v^2)/2 = 2000*22^2/2 = 1000*22^2 = 484KJ
Because car is not changing its potential energy, there is no work to be done on while changing it which means that all goes on changing kinetic energy (energy of motion)
Answer:
the normal force on the rock acts perpendicular to the bowl's surface.
Explanation:
As we know that Normal force is the reaction force of two contact surfaces which always act perpendicular to the contact surfaces
Here we know that the rock is moving inside the bowl
So Normal force on the rock must perpendicular to the surface of the bowl which always passes through the center of the bowl.
Since the rock is moving in vertical plane so it must have two acceleration
1) Tangential acceleration which will increase the magnitude of the speed along the tangential path
2) Centripetal acceleration which will change the direction of the rock
So here only correct option will be
the normal force on the rock acts perpendicular to the bowl's surface.
Answer:
Explanation:
A 60W bulb , consumes electrical energy of 60 J per second but it does not give out all the energy in the form of light . Most of the energy consumed by it is wasted in the form of heat . Only a fraction of energy is converted into light energy .
Hence, it is wrong to say that bulb supplies 60 J of light energy each second .
Looking at decibel scale tables on internet, a "quiet whisper 1 meter away" is generally reported to have a sound intensity of about 20 dB, while a jackhammer 3 meters away produces a sound of about 100 dB of intensity, so option a) could be the correct one.
However, the other options could be considered correct as well, because without knowing the exact sound power produced by the whisper or by the jackhammer it's impossible to calculate the exact sound intensity with precision, and since the values reported in the three options are very similar, all the three of them can be considered as valid.
