u = 3.0m/s = initial velocity, m = 95.0kg, v = 0m/s = final velocity of the sled because it comes to rest.
Δt = 15.0s.
The average force required to bring the sled to rest is equal to the change in momentum of the sled. From Newton's second law,
F = m(v-u)/Δt = 95×(0 – 3)/15 = –19N
F = –19N
The force is negative because it is against the direction of the initial motion or it is so because it is the force applied to bring sled to rest (to decelerate its motion)
When the same masses are heated by the same amount copper will heat up the fastest. Copper is a good conductor of heat that is why it easily heats up. Gold is not a good conductor of heat because of its stable properties.
