Please anyone help me dynamic quiz i need it for a test

[djmorfia]

http://www.filefreak.com/pfiles/38439/physics.JPG

need help on question 3 and 4

I don't understand what to do for those question can anyone show me an message below

 

[Astronuc]

In problem 3, one has a distance of 40 m in which to react then decelerate to a stop.

One knows the initial velocity 72 km/h (and one should convert to m/s) and a time of 0.6 s, during which some distance is traveled, d_reaction. The distance over which the car must decelerate is 40 m - d_reaction = d_stopping

One has to determine if the required deceleration exceeds the acceleration (or deceleration) associated with force of friction.

Reference for equations of motion
http://hyperphysics.phy-astr.gsu.edu/hbase/mot.html

For the pulley problem (or equivalent) -
http://hyperphysics.phy-astr.gsu.edu/hbase/hpul.html#c1

General problems for Newton's 2nd law -
http://hyperphysics.phy-astr.gsu.edu/hbase/N2st