91影视

FIGURE Q2.14 shows the velocity-versus-time graph for a moving object. At which lettered point or points:

a. Is the object speeding up?

b. Is the object slowing down?

c. Is the object moving to the left?

d. Is the object moving to the right?

A jet plane is cruising at 300 m/s when suddenly the pilot turns the engines up to full throttle. After traveling 4.0 km, the jet is moving at a speed of 400 m/s. What is the jet鈥檚 acceleration, assuming it to be a constant acceleration?

a. How many days will it take a spaceship to accelerate to the speed of light ( 13.0 * 10⁸ m/s) with the acceleration g? b. How far will it travel during this interval? c. What fraction of a light-year is your answer to part b? A light-year is the distance light travels in one year

When you sneeze, the air in your lungs accelerates from rest to 150 km/h in approximately 0.50 s. What is the acceleration of the air in m/s2 ?

A speed skater moving to the left across frictionless ice at 8.0 m/s hits a 5.0-m-wide patch of rough ice. She slows steadily, then continues on at 6.0 m/s. What is her acceleration on the rough ice?

A Porsche challenges a Honda to a 400 m race. Because the Porsche鈥檚 acceleration of 3.5 m/s² is larger than the Honda鈥檚 3.0 m/s² , the Honda gets a 1.0 s head start. Who wins? By how many seconds?

A car starts from rest at a stop sign. It accelerates at 4.0 m/s² for 6.0 s, coasts for 2.0 s, and then slows down at a rate of 3.0 m/s² for the next stop sign. How far apart are the stop signs?

For Questions 1 through 3, interpret the position graph given in each

figure by writing a very short 鈥渟tory鈥� of what is happening. Be creative!

Have characters and situations! Simply saying that 鈥渁 car moves

100 meters to the right鈥� doesn鈥檛 qualify as a story. Your stories should

make specific reference to information you obtain from the graph, such

as distance moved or time elapsed.

Julie drives 100 mi to Grandmother鈥檚 house. On the way to Grandmother鈥檚, Julie drives half the distance at 40 mph and half the distance at 60 mph. On her return trip, she drives half the time at 40 mph and half the time at 60 mph. a. What is Julie鈥檚 average speed on the way to Grandmother鈥檚 house? b. What is her average speed on the return trip?

Ball bearings are made by letting spherical drops of molten metal fall inside a tall tower鈥攃alled a shot tower鈥攁nd solidify as they fall.

a. If a bearing needs 4.0 s to solidify enough for impact, how high must the tower be? b. What is the bearing鈥檚 impact velocity?