How much work must be done to stop an 1 800kg vehicle travelling at 30 m/s?

810 kJ

Explanation:

Work done is equal to change in kinetic energy

W=∆KE

Change in kinetic energy is given by

∆KE=½m(v²-u²)

Where ∆KE is the change in kinetic energy, m is mass of the vehicle, v is final velocity while u is initial velocity.

Since the vehicle must come to rest, the final velocity is zero.

Substituting 1800 kg for m, 0 m/s for v and 30 m/s for u then

∆KE=½*1800(0²-30²)=-810, 000J

Converted into kJ

∆KE=-810 kJ

Therefore, work done is 810 kJ

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.