Aboy throws a ball of mass 0.25 kg straight upward with an initial speed of 20 m/s. when the ball returns to the boy, its speed is 17 m/s. how much work does air resistance do on the ball during its flight?

The work done is 13.875 J.

Explanation:

Given that,

Mass of ball = 0.25 kg

Initial speed = 20 m/s

Final speed = 17 m/s

We need to calculate the work done

Using formula of work done

Work done by the friction

Negative sign shows the friction always against displacement.

Hence, The work done is 13.875 J.

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.