The length of the metal threads at the end of a spark plug is called the
a. ground.
b. insulator.
c. shell.
d. reach.

d. reach

Explanation:

A spark plug is a device for igniting a definite volume of compressed air mixed with fuel. It has majorly three parts, center electrode which is an insulator, the thread reach at the end of the plug and a side metallic electrode. It is used in mechanical devices where combustion is of great importance.

c) up is the direction the magnetic force is acting on the charge.

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s