The answer they are looking for is the last one. However the last two are technically correct but the third one would result in negative work.
Answer:
harmful effects
1. that will cause air pollution
2. that will destroy our earth
Answer:
4086 J
Explanation:
The potential energy is transformed to kinetic energy less the frictional energy. Potential energy= mgh where m represent mass, g is acceleration due to gravity and h is the height of cliff
Since we have force of air resistance, work done due to air resistance will be product of force and distance

Substituting 10 Kg for m, 9.81 for g and 60 m for F then the kinetic energy at the bottom will be
KE= 10*9.81*60- (30*60)=4086 J
Answer:
The direction is due south
Explanation:
From the question we are told that
The energy of the electron is 
The earths magnetic field is 
Generally the force on the electron is perpendicular to the velocity of the elecrton and the magnetic field and this is mathematically reresented as

On the first uploaded image is an illustration of the movement of the electron
Looking at the diagram we can see that in terms of direction the magnetic force is


generally i cross k = -j
so the equation above becomes


This show that the direction is towards the south
Answer:
Speed of the alpha particle is
Explanation:
We have given charge on alpha particle 
Mass of the alpha particle 
Potential difference 
We have to find the speed of the alpha particle
From energy conservation we know that


