Momentum....Inelastic Collisions

Inelastic: term applied to a material that does not retrun to its original shape after it has been stretched or compressed

3 situations of inelastic collisions:
1. 2 objects collide and get stuck together
2. 2 objects stuck together and separate
3. 2 objects collide and one or both are deformed (E lost to heat)

 

astronaut 1 is moving toward astronaut 2 who is at rest

when they collide, they remain together (combine mass) and move with a new velocity

 

 

The big fish (object 1) is at rest v=0 km/h and the small fish(object 2) is moving toward the big fish at v=5 km/h

The big fish's mass is 4m and the small fish's mass is m

(4m)(0 km/h) + (m)(5 km/h) = (4m + m)(1 km/h)

the final velocity is positive because that is the same direction as the small fish's direction and its velocity was denoted as positive

 

 

 

Cart is object 1 and dropped brick is object 2

the cart's mass is 3 kg and the brick's mass is 2 kg

The cart's velocity is v=50 cm/s and the brick is not moving horizontally v=0 cm/s

The cart & brick are separate. When they collide, they are combined m=5 kg and move together at v=30 cm/s

(3 kg)(50 cm/s) + (2 kg)(0 cm/s) = (3 kg + 2 kg)(30 cm/s)

all objects are moving in same direction; therefore, all velocities are positive

 

 

 

Cart is object 1 and dropped brick is object 2

the cart's mass is 1 kg and the brick's mass is 2 kg

The cart's velocity is v=60 cm/s and the brick is not moving horizontally v=0 cm/s

The cart & brick are separate. When they collide, they are combined m=3 kg and move together at v=20 cm/s

(1 kg)(60 cm/s) + (2 kg)(0 cm/s) = (1 kg + 2 kg)(20 cm/s)

 

 

 

car is object 1 and truck is object 2

car and truck are moving toward each other , collide & lock together, and move towards the left

car's velocity = 20 m/s and truck's velocity = -20 m/s (neg. bcs in opp. dir.)

car's mass = 1000 kg and truck's mass = 3000 kg

(1000 kg)(20 m/s) + (3000 kg)(-20 m/s) = (1000 kg + 3000 kg)(-10 m/s)

(after collision car-truck are moving in same direction as truck before the collision, this direction was denoted as the negative direction; therefore the car-truck's velocity after the collision is negative)

 

 

 

car is object 1 and truck is object 2

car is moving toward the truck which is at rest, they collide & lock together, and move towards the right

car's velocity = 20 m/s and truck's velocity = 0 m/s (it is at rest)

car's mass = 1000 kg and truck's mass = 3000 kg

(1000 kg)(20 m/s) + (3000 kg)(0 m/s) = (1000 kg + 3000 kg)(5 m/s)

 

 

 

truck is object 1 and car is object 2

truck is moving toward the car which is at rest, they collide & lock together, and move towards the right

truck's velocity = 20 m/s and car's velocity = 0 m/s (it is at rest)

truck's mass = 3000 kg and car's mass = 1000 kg

(3000 kg)(20 m/s) + (1000 kg)(0 m/s) = (3000 kg + 1000 kg)(15 m/s)

 

 

 

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