A 2kg snowball moving at 22 m/s collides with a 7kg snowman's head. The snowball sticks to the snowman's head knocking it off. How much mass does the combined object have after the collision? How fast is the combined object moving at after the collision?

m₁v =(m₁+m₂)u

u= m₁v/(m₁+m₂)=2•22/(2+7)=4.9 m/s

To find the mass of the combined object after the collision, we need to add the masses of the snowball (2kg) and the snowman's head (7kg).

Combined mass = mass of snowball + mass of snowman's head
Combined mass = 2kg + 7kg
Combined mass = 9kg

So, the combined object has a mass of 9kg after the collision.

To find the speed of the combined object after the collision, we can use the law of conservation of momentum. According to this law, the total momentum before the collision is equal to the total momentum after the collision.

Initial momentum = Final momentum

The momentum is calculated by multiplying the mass of an object by its velocity.

For the snowball:
Initial momentum of snowball = mass of snowball × velocity of snowball
Initial momentum of snowball = 2kg × 22 m/s

Since the snowball sticks to the snowman's head, their velocities become the same after the collision. Let's say the final velocity is v m/s. So,

Final momentum of combined object = mass of combined object × velocity of combined object
Final momentum of combined object = 9kg × v

According to the law of conservation of momentum, the initial momentum of the snowball is equal to the final momentum of the combined object:

Initial momentum of snowball = Final momentum of combined object
2kg × 22 m/s = 9kg × v

Solving for v, we have:

v = (2kg × 22 m/s) / 9kg

Now, let's calculate it:

v = 44 m/s / 9
v ≈ 4.89 m/s

Therefore, the combined object is moving at approximately 4.89 m/s after the collision.