Two students noted that the acceleration of a car was -40 km/s^2. The first student said, “That can’t be right. You can’t have a negative acceleration.” The second student said, “That can’t be right. You can’t have s^2.” What would you say to each student to help them better understand how acceleration is described?

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?

Gordon is going for a run through the park, but it is cold outside. the low outside temperature could affect his personal safety.

Adolphin emits ultrasound at 100khz and uses the timing of reflections to determine the position of objects in the water. part a what is the wavelength of this ultrasound? assume that temperature of water is 20 degrees c. answer in cm