a. 7.0 m/s
First of all, we need to convert the angular speed (1200 rpm) from rpm to rad/s:

Now we know that the row is located 5.6 cm from the centre of the disc:
r = 5.6 cm = 0.056 m
So we can find the tangential speed of the row as the product between the angular speed and the distance of the row from the centre of the circle:

b. 
The acceleration of the row of data (centripetal acceleration) is given by

where we have
v = 7.0 m/s is the tangential speed
r = 0.056 m is the distance of the row from the centre of the trajectory
Substituting numbers into the formula, we find

Answer:
See below
Explanation:
KE = 1/2 m v^2 multiply both sides by 2
2 (KE) = mv^2 divide both sides by m
2(KE) / m = v^2 sqrt both sides
√ [(2KE)/m ] = v
Answer:the answer is true
Explanation:because as u add more coil/wrap more coil around the nail the field get stronger and stronger to attract more nails
Hope this helped
Please find attached photograph for your answer. Please do comment whether it is useful or not