An archer shoots a 2.0x10^-2 kg arrow at a target with a speed of 50 m/s. When it hits a target, it penetrates to a depth of 8.6x10^-2 m. What was the magnitude of the average force exerted by the target on the arrow? If the mass of the arrow is doubled, and the force exerted by the target on the arrow remains the same, by what multiplication factor does the penetration depth change?