A stone is thrown at an initial speed of 15 m/s from the top of a 20 m high cliff, while another stone is thrown
vertically from the bottom of the cliff upwards also at a speed of 15 m/s, the free-fall acceleration is equal to
a) After how long and at what height do the stones intersect?
b) Does the stone throw from below reach the top of the cliff?
A rocket is launched vertically from the ground at an initial speed of 200 m/s, after 10 seconds it explodes.
A ground observer located at a distance of 2000 meters, the same horizontal as the launch point, will hear the
blast noise after how long? The free-fall acceleration is 10 m/s2
, and the speed of sound in the
air 340 m/s.
On the Moon a stone is released at rest from a height of 20 meters, it falls under the action of the lunar free-fall
acceleration until reaching the ground with a speed v
. Determine how high the stone should be dropped on Earth
so that it hits the ground at the same speed v
. Free-fall acceleration on Earth
, free-fall acceleration on the Moon
The motion of a particle is described by the graph of the speed t as a function of time shown in the figure.
a) The acceleration of the particle;
b) Write the equation of the speed as a function of time;
c) What is the displacement between 3 s and 7 s.
The velocity-time graph
\( v=f(t) \)
gives the motion of a body:
a) The displacement between 1 s and 9 s;
b) The average speed between 1 s and 9 s;
c) The average acceleration between 1 s and 9 s.
A particle starts a straight motion with an initial velocity of 1 m/s, given the graph of the acceleration as a
function of time from the start of motion, find:
a) the velocity at t
b) The velocity at t
c) The velocity at t
d) Between, which time interval the speed decreases.
The equation of a motion is
S = 21 − 10 t + t2
where position S
is measured in
meters and time t
is measured in seconds:
a) Construct a table with values for t
from 0 to 8 s, and from the table plott the graph of the function;
b) When does the particle pass through the origin of the coordinate system?
c) When does the particle change its direction?