You see a sudden flash of light, then 6 seconds later you hear the thunder. Take the speeds of sound and light as 340 m⋅s−1340 m⋅s−1 and 3×108 m⋅s−13×108 m⋅s−1, respectively. How far away was the lightning strike? Remember to think about significant figures.

The lightning strike was _____ km away.

(A reminder: This test is for assessment and, because the course runs on-demand, we cannot give you the answers and so you will not receive feedback on this test. If you can't do a question and you need feedback, we suggest that you go review the relevant lesson and then do the quiz: the quiz questions do have feedback.)

2) Andromeda Galaxy

The Andromeda galaxy is about 2.5 million light-years or 2.4×1022 m2.4×1022 m from our Milky Way galaxy, and the component of its velocity towards us is about 3.0×105 m⋅s−13.0×105 m⋅s−1. If it maintained this velocity component towards us, how long would it take to cover 2.4×1022 m2.4×1022 m?

3) Keeping up the average

You have boasted to your friends that you can ride your bicycle at 30 kph (km per hour) over a 30 km race comprising two 15 km laps. However, when you finish the first lap, your coach tells you that your average speed so far is only 15 kph. How fast must you ride to bring your average speed up to 30 kph.?

4) Catching up

Jane's brother Andrew leaves home for school at 8:00 am. He walks at 3.3 kph. At 8:20 am Jane discovers that Andrew has left his homework at home. She decides to follow him on her bicycle and give him his homework, but she wants to be back home in time for an online test at 9 am. What is the minimum constant speed at which she needs to ride? (Hint: At what time of day will they meet?)

Jane must ride at least ______ kph.

5) Speeding car

A car accelerates with a constant acceleration of 1.5 m⋅s−21.5 m⋅s−2 along a long straight road. How long does it take the car to accelerate from 100 kph to 110 kph, and how far does it travel while doing so? [Hint: watch your units and sig figs! Because there is no other information, take the speeds as three significant figures]

It takes ______ seconds to accelerate to 110 kph. While accelerating, the car travels _____ m.

Separate your answers with a comma. Example: a, b

6) Hockey

A (field) hockey player is running north at a speed of 8 m⋅s−18 m⋅s−1. A ball is coming directly towards her from the north at a speed of 18 m⋅s−118 m⋅s−1. She swings her stick forward, directly north, at a speed of 6 m⋅s−16 m⋅s−1 measured in her own frame of reference. What is the speed of the ball with respect to the hockey stick?

Relative to the hockey stick, the ball is traveling at ____ m⋅s−1 m⋅s−1.