Answer:
v=5.86 m/s
Explanation:
Given that,
Length of the string, l = 0.8 m
Maximum tension tolerated by the string, F = 15 N
Mass of the ball, m = 0.35 kg
We need to find the maximum speed the ball can have at the top of the circle. The ball is moving under the action of the centripetal force. The length of the string will be the radius of the circular path. The centripetal force is given by the relation as follows :

v is the maximum speed

Hence, the maximum speed of the ball is 5.86 m/s.
Answer: 
The chromium nucleus will complete the reaction.
Explanation:
The given reaction is a type of radioactive nuclei decay:
Positron emission: It is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. This is also known as
-decay. In this the mass number remains same.

Now according to the given reaction:

The chromium nucleus will complete the reaction.
D
Giddy UP!!!!!!!!!!!!!!!!!!!!!
Answer:
A scalar quantity is defined as the physical quantity that has only magnitude, for example, mass and electric charge. On the other hand, a vector quantity is defined as the physical quantity that has both magnitude as well as direction like force and weight.
Explanation:
Since the balloon is not accelerating means that the net force on the balloon is zero. This implies that the weight of balloon must be equal to the buoyant force on balloon.
Hence, the buoyant force equals the weight of air displaced by the balloon, also 20,000 N.
Weight of the air displaced = density of air × volume
The density of air at 1 atm pressure and 20º C is 1.2 kg/m³
the volume V = 20,000/(1.2×9.8) = 1700 m³