Answer:
Velocity= 19.05 m/s
Kinetic energy= 3.08 J
Explanation:
The corn possess potential energy. Feom law of conservation of energy, all the potential eneegy will be converted to kinetic energy, with negligible friction.
Potential energy, PE= kinetic energy, KE
Potential energy is given by mgh while kinetic energy is given by 
Equating
Making v the subject of the formula then

Substituting 9.81 m/s2 for g and 18.5 m for h then the velocity will be

To get the kinetic eneegy, since PE=KE AND KE is

Substituting v with 19.05 and m with 0.017 kg we have

This can also be achieved by mgh since PE=KE hence 0.17*9.81*18.5=3.085245 J and the results are slightly different due to small energy losses and rounding off of values.
Answer:
car1: a=3.1m/s^2 , car2: a=6.1m/s^2
(a) 1/2*3.1*t^2= 1/2*6.1*(t-0.9)^2
1.55t^2= 3.05(t^2-1.8t+0.81)= 3.05t^2-5.49t+2.4705
1.5t^2-5.49t+2.4705= 0
t= 3.13457 = 3.14[s] after.
(b) d= 1/2*3.1*3.13457^2= 15.23[m] approx.
(c) car1: v=at = 3.1*3.13457= 9.717m/s
car2: v=at = 6.1*(3.13457-0.9)= 13.631m/s
13.631-9.717= 3.914 = 3.91[m/s] faster than car1.
A :-) F = mv^2 by r
Given - m = 500 kg
v = 80.0 m/s
r = 450 m
Solution -
F = mv^2 by r
F = 500 x (80)^2 by 450
F = 500 x 6400 by 450
( cut 500 and 450 because 5 x 100 = 5 , 5 x 90 = 450 and also 90 and 6400 because 90 x 70 = 6400 )
F = 100 x 70
F = 7000
.:. The centripetal force is 7000 N
The correct answer is:
Product of their masses
In fact, the gravitational pull between two objects is given by:

where
G is the gravitational constant
m1 and m2 are the masses of the two objects
r is the distance between the centres of the two objects
From the equation, we immediately see that the gravitational attraction is directly proportional to the product of the masses.