Answer:
10ms⁻¹
Explanation:
Simply we can consider a motion equation
V = U + a*t
since in upward motion velocity decreases ,
amount of velocity decreased = u-v
V=U -gt ( g =10ms⁻² downwards)
u-v =10*1 ms⁻¹
decreased amount of velocity in a second = 10ms⁻¹