Answer:
Yes it is possible to control to some extent.
Explanation:
In general there are two types of magnets : permanent and temporary (electromagnets).
Electromagnets can be controlled since it basically depends on electricity. By switching on and off the electric supply the magnets also can be switched on and off respectively. We can also control the intensity of magnetic power.
On the other hand permanent magnet cannot be switched on and off but the magnetic properties can be altered event to an extent when it loses all its magnetic properties. It can be caused by high temperature, physical impact and also exposure to other magnetic fields. For every element there is a point of temperature called curie temperature above which the permanent magnet loses its magnetic properties. This can be brought back again by induced magnetism. The only issue is that induced magnetism work in most cases but not in all.
 
        
             
        
        
        
Solve for Speed: 16+20=36 km in 11 hrs
Answer: speed = 
3.27273 kilometers per hourTo solve for speed or rate use the formula for speed, s = d/t which means speed equals distance divided by time.
<span>speed = distance/time</span>
 
        
        
        
Answer:
acceleration 8 km/h/s south
Explanation:
First of all, let's remind that a vector quantity is a quantity which has both a magnitude and a direction. 
Based on this definition, we can already rule out the following two choices:
distance: 40 km
speed: 40 km/h
Since they only have magnitude, they are not vectors.
Then, the following option:
velocity: 5 km/h north
is wrong, because the car is moving south, not north.
So, the correct choice is
acceleration 8 km/h/s south
In fact, the acceleration can be calculated as

where 
v = 40 km/h is the final velocity
u = 0 is the initial velocity
t = 5 s is the time
Substituting,

And since the sign is positive, the direction is the same as the velocity (south).
 
        
             
        
        
        
Wavelength of the water wave is 8 m
Explanation:
- Wavelength measures the distance between two successive crests or troughs of the wave. It is given by the following equation
λ = v/f, where f is the frequency, v is the velocity of the wave 
Here, v = 20 m/s and f = 2.5 Hz
⇒ λ = 20/2.5
       = 8 m
 
        
             
        
        
        
When the ball starts its motion from the ground, its potential energy is zero, so all its mechanical energy is kinetic energy of the motion:

where m is the ball's mass and v its initial velocity, 20 m/s.
When the ball reaches its maximum height, h, its velocity is zero, so its mechanical energy is just gravitational potential energy:

for the law of conservation of energy, the initial mechanical energy must be equal to the final mechanical energy, so we have

From which we find the maximum height of the ball:

Therefore, the answer is 
yes, the ball will reach the top of the tree.