Broken or bruised ribs. Introduction. Broken (fractured) or bruised ribs are usually caused by a fall or blow to the chest, or occasionally by severe coughing. They can be very painful, but will normally improve within about three to six weeks. If you think you've injured your ribs, you'll often be able to look after yourself at home.
The average speed of an object is defined as the distance traveled divided by the time elapsed. Velocity is a vector quantity, and average velocity can be defined as the displacement divided by the time. For the special case of straight line motion in the x direction, the average velocity takes the form:
Boy, this is easy!. Unfortunately, however, the answer is not 90 miles/hour. Here's why: You know that average velocity = distance/time (v = d/t). In order to have an average speed of 60 miles/hour over a distance of 60 miles, you must complete the trip in 1 hour:But Susie has already taken an hour (it takes 1 hour to go 30 miles with an average speed of 30 miles/hour) - and she is only half way!f a car's average speed is 65 miles per hour, this means that the car's position will change (on the average) by 65 miles each hour. Average speed is a rate. In kinematics, a rate is always a quantity divided by the time taken to get that quantity (the elapsed time).