The first and third choices on the list will attract, because UNlike poles are facing across the gap.
Choice #1: . . . [S]-----[N] . . . [S]-----[N]
Choice #3: . . . [N]-----[S] . . . [N]-----[S]
use Newton's gravitational law and 2nd law .....
Explanation:
Elastic collision is said to occur if the total kinetic energy is not conserved and if there is a rebound after collision
Step one
Analysis of the problem
Immediately after impact the car's velocity was zero making it a perfect elastic collision
Step two
Given
Mass of car M1=1800kg
Mass of truck M2=5200kg
Initial velocity of Car U1=44m/s
Initial velocity of truck U2=21m/s
Final velocity of car V1= 0m/s
Final velocity of truck V2=20m/s
Step three
According to the principle of conservation of momentum
Total momentum before collision
=M1U1+M2U2
Total momentum after impact
=M1V1+M2V2
M1U1+M2U2 =M1V1+M2V2
Substituting our data into the expression we have 1500*44+5800*21=1500*0+5800*20
=66000+1218000=11600
1284000=11600
From the solution the momentum before impact is 1284000Ns
Momentum after impact is 11600Ns
This is indicating that after impact there was loss in momentum as a result of the car having a velocity of zero
You could be counting while running
