4. A driver takes 3.5 s to react to a complex situation. How far does the vehicle travel before the driver initiates a physical response to the situation (i.e., putting his or her foot on the brake)

This question is incomplete, the complete question is;

A driver takes 3.5 s to react to a complex situation while driving at a speed of 60 mi/h.

How far does the vehicle travel before the driver initiates a physical response to the situation (i.e., putting his or her foot on the brake)

the distance travelled by the vehicle, before the driver initiates a physical response is 308 ft

Explanation:    

Given that;

Reaction time t = 3.5 sec

Speed S = 60 mi/h

we convert mile to foot and hour to seconds

so

Speed S = 60 mi/h =  (60×5280)/(60×60) = 316800/3600 = 88 ft/sec

Now, The distance travelled by vehicle before the driver  initiates physical response is equal to Lag distance. i.e

Lag distance = V × t

we substitute

Lag distance = 88 ft/sec  3.5 sec

Lag distance = 308 ft

Therefore, the distance travelled by the vehicle, before the driver initiates a physical response is 308 ft

Linear expansivity is a property specific to a material and hence is constant.

Explanation:

Linear expansivity of the material will be constant irrespective of the shape and size of the material because it is a specific property.

It is a tendency of a material to expand in response to the increase in temperature.

The mathematical expression is given as:

where:

= change in temperature

L= initial length of the specimen

= linear expansivity

=change in length