Aspaceship travels at constant speed, vg = c away from earth. sixteen minutes after departure, according to the ship's clock, the pilot learns that a bomb has been placed on the ship. the bomb is programmed to explode 51 minutes after departure. (i) the pilot immediately escapes and returns to earth. the moment the escape pod leaves the ship the pilot sends a radio message to earth. show that the distance of the ship from earth in earth's reference frame, when the pilot escapes, is 30 light minutes (where 1 light minute is the distance travelled by light in 1 minute, 1 lmin = cx 1 min). calculate how many minutes after departure the message is received on earth. (ii) the escape pod blasts off from the ship with speed, v, = 24 c with respect to the ship and towards earth. unbeknown to the pilot, the bomb is actually in the escape pod. show that the speed of the escape pod with respect to earth is up= show that the distance of the escape pod from earth, in earth's reference frame, when the pod explodes, is light minutes. calculate how many minutes after departure earth sees the explosion. (iii) draw a spacetime diagram in earth's reference frame, depicting the world- lines of the ship, the escape pod, the pilot's signal and the light from the explosion. (iv) months later, the pilot's wrist-watch is recovered, which stopped at the moment of the explosion. the watch was set to 00: 00 at departure. state what was shown on the display.

Which units can be used to measure length or distance? check all that apply. gram meter kilometer liter inch

Follow these directions and answer the questions. 1. shine a pencil-thin beam of light on a mirror perpendicular to its surface. (if you don't have a laser light as suggested in the video, you can make a narrow beam from a flashlight by making a cone from black construction paper and taping it over the face of the flashlight.) how does the light reflect? how does the relationship of incident to reflected ray relate to the reflection of water waves moving perpendicular to a barrier? 2. shine a pencil-thin beam of light on a mirror standing on a sheet of paper on the table (or floor) so that you can mark the incident ray and reflected ray. (you can support the mirror from the back by taping it to a wooden block.) 3. mark a line on the paper representing the reflective surface. (the reflective surface of a mirror is usually the back edge.) 4. draw a dashed line perpendicular to the mirror surface at a point where the incident and reflected ray meet. this perpendicular is called a normal to the surface. 5. measure the angles between the rays and the normal. the angle of incidence is the angle formed by the incident ray and the normal to the surface. the angle formed by the reflected ray and normal is called the angle of reflection (r). what is the angle of incidence? what is the angle of reflection? 6. repeat for several different angles. (see report sheet for details.) what appears to be the relationship between the angle of incidence and angle of reflection? in science 1204, what was the relationship for these two angles made by the reflection of waves in a ripple tank? 7. roll a ball bearing so that it hits a fixed, hard surface (a metal plate) at several angles (including head-on). observe the way in which the ball bearing reflects. what generalization can you make about how a ball bearing reflects from a wall? have you proved that light can only behave like a wave?

Awoman stands a distance d from a loud motor that emits sound uniformly in all directions. the sound intensity at her position is an uncomfortable 2.0×10-3 w/m2. at a distance 2.6 times as far from the motor, what are (a) the sound intensity and (b) the sound intensity level relative to the threshold of hearing?