<span>If you spin fast enough, the impact of the glad will break the blade of grass before it can move out of the way. In the same way that if you kick an empty can, it will move out of the way, but if you shoot it with a gun, the bullet will cut through the can before it can move. Keep in mind a mower blade turns at probably 10,000 RPMs.</span>
1) In any collision the momentum is conserved
(2*m)*(vo) + (m)*(-2*vo) = (2*m)(v1') + (m)(v2')
candel all the m factors (because they appear in all the terms on both sides of the equation)
2(vo) - 2(vo) = 2(v1') + (v2') => 2(v1') + v(2') = 0 => (v2') = - 2(v1')
2) Elastic collision => conservation of energy
=> [1/2] (2*m) (vo)^2 + [1/2](m)*(2*vo)^2 = [1/2](2*m)(v1')^2 + [1/2](m)(v2')^2
cancel all the 1/2 and m factors =>
2(vo)^2 + 4(vo)^2 = 2(v1')^2 + (v2')^2 =>
4(vo)^2 = 2(v1')^2 + (v2')^2
now replace (v2') = -2(v1')
=> 4(vo)^2 = 2(v1')^2 + [-2(v1')]^2 = 2(v1')^2 + 4(v1')^2 = 6(v1')^2 =>
(v1')^2 = [4/6] (vo)^2 =>
(v1')^2 = [2/3] (vo)^2 =>
(v1') = [√(2/3)]*(vo)
Answer: (v1') = [√(2/3)]*(vo)
Answer:
<u> a = V final 2___v initial2</u>
28
Explanation:
By definition for contant acceleration <u>a = V final ___v initial</u>
t
Furthermore the average speed is <u>V abg = v initial +v final</u>
2
Combine these relationships to eliminate t. 8 = Vabg t.
