1.commensalism
2. pred-prey
3. parasite-host
4.commensalism
Answer:
Electric field, 
Explanation:
It is given that,
Mass of sphere, m = 2.1 g = 0.0021 kg
Charge, 
We need to find the magnitude of electric field that balances the weight of a plastic spheres. So,

a = g



or

Hence, the magnitude of electric field that balances its weight is
. Hence, this is the required solution.
Answer:
The power output of the first motor is, P = 2.0 x 10⁴ watts
Explanation:
Given data,
The height of the building, h = 10 m
The mass of the elevator, m = 1000 kg
The time duration of the motor to do this work, t = 5.0 s
The force acting on the elevator,
F = m x g
= 1000 x 9.8
= 9800 N
The work done by the elevator,
W = F x h
= 9800 x 10
= 98000 J
The power output of the first motor,
P = W / t
= 98000 / 5
= 19600 watts
= 1.96 x 10⁴ watts
Hence, the power output of the first motor is, P = 2.0 x 10⁴ watts
Answer:

Explanation:
Let assume that ball strikes a vertical wall in horizontal direction. The situation can be modelled by the appropriate use of the definition of Moment and Impulse Theorem, that is:


The average force acting on the ball during the collision is:

