To test the resiliency of its bumper during low-speed collisions, a 2 010-kg automobile is driven into a brick wall. The car's bumper behaves like a spring with a force constant 4.00 106 N/m and compresses 3.18 cm as the car is brought to rest. What was the speed of the car before impact, assuming no mechanical energy is transformed or transferred away during impact with the wall?

Vi = 2 m/s

Explanation:

First we find the force applied to the car by wall to stop it. We use Hooke's Law:

F = kx

where,

F = Force = ?

k = spring constant = 4 x 10⁶ N/m

x = compression = 3.18 cm = 0.0318 m

Therefore,

F = (4 x 10⁶ N/m)(0.0318 m)

F = 127200 N

but, from Newton's Second Law:

F = ma

a = F/m

where,

m = mass of car = 2010 kg

a = deceleration = ?

Therefore,

a = 127200 N/2010 kg

a = 63.28 m/s²

a = - 63.28 m/s²

negative sign due to deceleration.

Now, we use 3rd equation of motion:

2as = Vf² - Vi²

where,

s = distance traveled = 3.18 cm = 0.0318 m

Vf = Final Speed = 0 m/s

Vi = Initial Speed = ?

Therefore,

2(- 63.28 m/s²)(0.0318 m) = (0 m/s)² - Vi²

Vi = √4.02 m²/s²

Vi = 2 m/s

freezing

deposition

condensation

explanation;

melting also called fusion is the process where solid becomes liquid, sublimation is the process where solid becomes gaseous without first changing to liquid, deposition involves change from gaseous to solid state, freezing involves change from liquid to solid, boiling or evaporation involves change of liquid to gaseous state, while condensation is the change from gaseous state to liquid state.

endothermic reactions involves absorption of heat from the surroundings or the environment while exothermic reactions involves loss of heat energy to the surroundings.

in this case, sublimation, evaporation and melting are endothermic reactions (gain energy from the environment) while, freezing, deposition and condensation are exothermic (loss of energy to the surroundings) reactions.

your answer would be fusion