A horse and her rider have a combined mass of 120 kg and is traveling 45 m/s down a dirt road. She increases her speed to 85 m/s in 4 seconds., what force did it require for her to speed up?

1200N

Explanation:

Given parameters:

Mass of the horse and rider  = 120kg

Initial velocity  = 45m/s

Final velocity  = 85m/s

Time taken  = 4s

Unknown:

Force required to speed up = ?

Solution:

According to Newton's second law of motion;

        Force  = mass x acceleration

Acceleration  =  

    v is the final velocity

    u is the initial velocity

    t is the time taken

 Now;

         Force  =  mass x    

Insert the parameters and solve;

      Force  = 120 x  = 1200N

a electromagnetic waves

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s