Final answer:
To find the contact force between blocks Q and R, apply Newton's second law to the system of blocks and calculate the acceleration. Once you have the acceleration, use it to find the contact force between blocks Q and R.
option d is the correct
Step-by-step explanation:
The contact force between blocks Q and R can be found by applying Newton's second law to the system of blocks. The force applied to the 8 kg block will cause it to accelerate. To find the acceleration of the system, we can use the formula F = ma, where F is the net force acting on the system and m is the total mass of the system.
Given that the applied force is 18 N and the masses of block P, Q, and R are 8 kg, 2 kg, and unknown respectively, we can write the equation as: 18 N = (8 kg + 2 kg + m) * a. Since we know the mass of block P and Q, we can substitute them into the equation to solve for the mass of block R. Once we have the mass of block R, we can substitute it back into the equation to find the acceleration of the system.
Finally, we can use Newton's second law again to find the contact force between blocks Q and R. The contact force is equal to the mass of block Q multiplied by the acceleration of the system. Therefore, the contact force between blocks Q and R is 2 kg * acceleration.