I got this answer wrong in my homework;

"A body moving in the positive x direction passes the origin at time t = 0. Between t = 0 and t = 1 second, the body has a constant speed of 15 meters per second. At t = 1 second, the body is given a constant acceleration of 5 meters per second squared in the negative x direction. The position of the body at t = 10 seconds is..."

Apparently the correct answer is -53m... I keep getting -67m. Why is it -53m? Can someone show me please?

Question

I got this answer wrong in my homework; 

"A body moving in the positive x direction passes the origin at time t = 0. Between t = 0 and t = 1 second, the body has a constant speed of 15 meters per second. At t = 1 second, the body is given a constant acceleration of 5 meters per second squared in the negative x direction. The position of the body at t = 10 seconds is..." 

Apparently the correct answer is -53m... I keep getting -67m. Why is it -53m? Can someone show me please?

anonymous · Answer

hmm.. .. think properly.. you are right in gettnig -67.. that is the TOTAL DISPLACEMENT from t=1s.. to t=10s.. 

but at t=1s the body is NOT at the origin.. if it was.. then you are right.. since at t=0 the body already has a speed of 15m/s in the positive direction.. at t=1s.. it has travelled some distance in positive.. this should help :P