The answer is (A) the object must be at rest.
When all of the forces acting on an object balance, the net force is zero and hence the object will not move.
Yes, the direction might also change under some special circumstances.
Answer:

Explanation:
In this case, since the charged particle moves in circular motion, the centripetal force is equivalent to the magnetic force.

Answer:

Explanation:
Moment of inertia of given shell
where
M represent sphere mass
R -sphere radius
we know linear speed is given as 
translational 
rotational 
total kinetic energy will be


fraction of rotaional to total K.E

Answer: It wouldn't be as modern as today is we would be back to using oil and other things from back then there wouldn't be cars everything would be less machined.
Answer:
x = 5[km]
Explanation:
We must convert the time from minutes to hours.
![t=30[min]*\frac{1h}{60min}= 0.5[h]\\](https://tex.z-dn.net/?f=t%3D30%5Bmin%5D%2A%5Cfrac%7B1h%7D%7B60min%7D%3D%200.5%5Bh%5D%5C%5C)
We know that speed is defined as the relationship between space and time.

where:
x = space [m]
t = time = 0.5 [h]
v = velocity [m/s]
Now replacing:
![x = 10[\frac{km}{h} ]*0.5[h]\\x=5[km]](https://tex.z-dn.net/?f=x%20%3D%2010%5B%5Cfrac%7Bkm%7D%7Bh%7D%20%5D%2A0.5%5Bh%5D%5C%5Cx%3D5%5Bkm%5D)