please can you help me with all!! please

it's C language! i know the answer for one !! i nesd help for 2 to 4

1. A physics student gets unexpected results when using the code float force=G*massimass2/r* to compute values according to the formula F=Gm:ma/?. Explain the problem and correct the code. 2. Write a program to calculate the distance between a point and the original point in a 2- D Cartesian coordinate system. Your program should let the user to enter two numbers as the coordinates of the point. Your output should look similar to this: Enter the value of x and y for a point: 5 6 The distance to the original point is: 7.810250 3. Write a program to convert time in seconds into time in hours, minutes, and seconds. Your output should look similar to this: Enter a time in seconds : 25587 The time is 7 hours, 6 minutes, and 27 seconds 4. Write a program to ask the user to enter a three-digit number, then prints the number with its digits reversed. Your output should look similar to this: Enter a three-digit number: 891 The reversed number is: 198