An engineer in a locomotive sees a car stuck on the track at a railroad crossing in front of
the train. When the engineer first sees the
car, the locomotive is 330 m from the crossing
and its speed is 21 m/s.
If the engineer’s reaction time is 0.44 s,
what should be the magnitude of the minimum deceleration to avoid an accident?
Answer in units of m/s
2
.

A1200 kg car traveling north at 10 m/s is rear-ended by a 2000 kg truck traveling at 30 m/s. what is the total momentum before and after the collision?

Heena wants to measure the volume of a ball that is 24 cm across. how should she set up her equation?

Unpolarized light falls on two polarizer sheets whose transmission axes are at right angles. a third polarizer is placed between the first two so that its axis makes a 52-degree angle with the axis of the first polarizer. a) what fraction of the incident light intensity is transmitted through the first polaroid? b) what fraction of the incident light intensity is transmitted through the second polaroid? c) what is the angle of polarization of the light that enters the third polaroid? d) what fraction of the incident light intensity is transmitted through the third polaroid. e) what happens if the middle polaroid is removed?