Speed depends on time and distance.
fluid friction<span> occurs when an object moves through a liquid or gas. the force needed to overcome </span>fluid friction <span>is usually less then that needed to overcome </span>sliding friction<span>. the </span>fluid<span> keeps the surface from making direct contact and thus </span>reducing friction<span>.</span>
Answer:
Explanation:
Let after time t , Tina catches up David .
Distance travelled by them are equal ,
Distance travelled by Tina
s = ut + 1/2 a t²
= .5 x 2.10 t²
= 1.05 t²
Distance travelled by David
= 30 t ( because of uniform velocity )
1.05 t² = 30t
t = 28.57 s
Distance travelled by Tina
= 1/2 a t²
= .5 x 2.10 x 28.57²
= 857 m approx.
Answer:
False
Explanation:
Let's consider the definition of the angular momentum,
where 
is the moment of inertia for a rigid body. Now, this moment of inertia could change if we change the axis of rotation, because "r" is defined as the distance between the puntual mass and the nearest point on the axis of rotation, but still it's going to have some value. On the other hand,
so 
unless 
║ 
.
In conclusion, a rigid body could rotate about certain axis, generating an angular momentum, but if you choose another axis, there could be some parts of the rigid body rotating around the new axis, especially if there is a projection of the old axis in the new one.
