To solve this problem, we can use the principle of conservation of momentum, which states that the total momentum of a system remains constant if there are no external forces acting on it. We can set the momentum of the asteroid before the collision equal to the momentum of the asteroid-Silly Putty system after the collision.
The momentum of the asteroid before the collision is:
P_before = m_ast * v_ast
where m_ast is the mass of the asteroid and v_ast is its velocity.
The momentum of the asteroid-Silly Putty system after the collision is:
P_after = (m_ast + m_sp) * v_final
where m_sp is the mass of the Silly Putty, v_final is the velocity of the asteroid-Silly Putty system after the collision, which we assume to be zero.
We can equate these two expressions for momentum and solve for the mass of the Silly Putty:
m_sp = (m_ast * v_ast) / (-v_final)
Substituting the given values:
m_ast = 25,000 kg
v_ast = 1500.0 m/s
v_final = -100.0 m/s
m_sp = (25,000 kg * 1500.0 m/s) / (-(-100.0 m/s))
m_sp = 375,000 kg m/s / 100.0 m/s
m_sp = 3750 kg
Therefore, we would need 3750 kg of Silly Putty to stop the asteroid if we launched it at a velocity of -100.0 m/s.