Answer to Question #296368 in Mechanics | Relativity for micheal

Question

A. An airliner must reach a speed of 110 m/s to take off. If the available runway is 2.4 km

and the aircraft accelerates uniformly from rest at one end, what minimum acceleration

must be available if it is to take off?

B. A speeding motorist driving a car, passes a traffic police officer on a stationary

motorcycle. The police officer immediately gives chase: his uniform acceleration is

4ms-2

, and by the time he draws level with the speeding car, the police officer is

travelling at 30ms-1

.

i. How long did it take for the police officer to catch the car?

ii. If the speeding motorist continued to travel at a steady speed during the

chase, what was his speed?

C. A stone is thrown vertically upwards with a speed of 24.0 ms-1

. Using g = 9.8 ms-2

and

ignoring air resistance:

i. How much time is required to reach this height?

ii. Why are there two answers to (ii.)?

iii. Sketch the velocity-time graph for the stone, from it is released until it

returns to the thrower.

Answer 1

A.

$a=\frac{v^2}{2l}=2.52~\frac m{s^2}.$

B.

1.

$t=\frac va=7.5~\frac ms,$

2.

$v_1=v=30~\frac ms.$

C.

$t=\sqrt{\frac {2h}g}=2.2~s.$