중량 300kg의 말이 50cm 앞에 벽에 충돌 했을 때

충돌량을 구해야 되는데
     
조건은. 말은 300kg 
                
             50cm.에 도달하는데 0.25초  
              
             충돌했을때 접촉 시간이 0.5초
                                 
             라고 할 때

       f=ma 라고 하던데 그럼 
      
               300kg x 2m/s
           600n x 0.5
          300n이 충돌량이 되는건가요?