You have to solve this by using the equations of motion:
u=3
v=0
s=2.5
a=?
v^2=u^2+2as
0=9+5s
Giving a=-1.8m/s^2
Then using the equation:
F=ma
F is the frictional force as there is no other force acting and its negative as its in the opposite direction to the direction of motion.
-F=25(-1.8)
F=45N
Then use the formula:
F=uR
Where u is the coefficient of friction, R is the normal force and F is the frictional force.
45=u(25g)
45=u(25*10)
Therefore, the coefficient of friction is 0.18
Hope that helps
        
             
        
        
        
Answer:
a) True.
Explanation:
If you turn the wheel in the direction of the turn before beginning the turning maneuver then it's possible that there might be not enough space available for turning and also if you are waiting for the traffic to get clear with rear  ended then it will get pushed forward onto the coming traffic. 
 
        
             
        
        
        
Answer: 0.72 grams
Explanation: Mass can be extracted from the formula of density. D=M/V where D is density and V is volume. Therefore:
18 g/cm^3 = M(25 cm^3) --> Divide by 18g/cm^3 by 25 cm^3 to isolate mass. --> <u>0.72 =M </u> --> Now, to find out which unit you need to use for mass, just look at the density. You can see it is in g/cm^3, and cm^3 was already used for the volume. Thus, gram units are left, so that will be the unit needed, making the final answer 0.72 grams. Hope this helps :)
 
        
             
        
        
        
Answer:

Explanation:
At some distance from the Earth the force of attraction due to moon is balanced by the force due to Moon
so we will have

now we have


so we will have

Now by energy conservation


