Answer : 
Explanation :
Given that,
Charge of particle 1 = 
Distance x = 6 cm
Charge of particle 2 = 
Distance x = 27 cm
Total distance = 

Particle 1 is at (6,0) and particle 2 is at (27,0) .
Therefore, midway (16.5, 0)
Now, 
Formula of electric field

Now, the the electric field due to particle 1



Similarly, the electric field due to particle 2

Resultant Electric field


Hence, this is the required answer.
I think C and D are the best way to describe projectile motion since both left the ground and stayed aloft for a small or large amount of time. A and B are example of motion but not projectile
Answer:
The velocity of the center of mass of the two-object system remains constant during the experiment.
Answer:
W = 68.6 N
Explanation:
Given that,
Force acting on a right side = 30 N
Mass of the object, m = 7 kg
The force of friction acting on the car = 3 N
We need to find the weight of the object.
The weight of an object is given by :
W = mg
Substitute all the values,
W = 7 × 9.8
W = 68.6 N
So, the weight of the object is 68.6 N.