Bumpers on cars are not of much use in a collision. to see why, calculate the average force a bumper would have to exert if it brought a 1200-kg car (a so-called compact model) to a rest in 15 cm when the car had an initial speed of 2.0 m/s (about 4.5 mph). (bumpers are built with springs that compress to provide a stopping force without, hopefully, denting the metal.)

1186.67 N

Explanation:

u = Initial velocity = 2 m/s

v = Final velocity = 0

s = Displacement = 0.15 m

a = Acceleration

m = Mass = 1200 kg

Equation of motion

Force

The force that the bumper will exert is 1186.67 N

F = 16 kN

Explanation:

given,

mass of the car = 1200 kg

distance travel to stop = 15 cm

initial speed of car = 2 m/s

average force = ?

using equation of motion

v² = u² + 2 as

0² = 2² - 2 a × 0.15                   ∵ -ve sign because of deceleration

0.3 a = 4

F = m a

F = 1200 × 13.33

F = 15996 N

F = 16 kN

the average force on the bumper is equal to F = 16 kN

specific latent heat of fusion, lf, of a substance is defined as the amount of heat required to change a unit mass of the substance from solid to liquid state, without any change in the temperature.

explanation:

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.