ANSWER:
d) all of these
STEP-BY-STEP EXPLANATION:
If no net force acts on an object, it remains at rest if it is initially at rest, or maintains its speed if it is initially in motion. Objects can move at a constant speed while experiencing zero net force; if the speed is constant, the acceleration is zero.
So the correct answer is at rest, zero acceleration, and constant speed, that is option d) all of these
Turn into stone. this will cause erosion for magma to turn to stone
Answer: the same direction I.e to the left.
Explanation:
The component perpendicular to the contact surface is such that will stop the relative motion and, in case of elastic collision like here, return the system to the same kinetic energy. So ball hitting immovable surface will have the same speed (magnitude of velocity) as before the collision.
There will also be parallel force caused by friction, but it has to be treated separately for two reasons:
The perpendicular force is limited to coefficient of friction times the normal force. If that is not enough to stop the ball, it will skid on the surface.The perpendicular force, and this depends on the specific geometry, does not pass through the centre of mass of the ball. Therefore it imparts a moment on the ball that causes it to start rotating. And once the ball is rotating so that the point of contact is stationary, there is no momentum to cause any friction force anymore and the friction force disappears and stops decelerating the ball.
So what happens is that the vertical component of the velocity will be reversed, while the horizontal component will be somewhat reduced with the corresponding amount of kinetic energy transferred to energy of rotation. The rotation will always eliminate the friction force before the horizontal component of velocity is zeroed, so the ball will always continue in the same direction, just a bit slower.
If you instead threw an elastic box (which could not start rotating freely) it could actually bounce back.
Answer:
0.6375 m/s
Explanation:
Let x be the distance of the man from the building
from the figure attached
initially the value of x=12
Given:
where the negative sign depicts that the distance of the man from the building is decreasing.
Now, Let The length of the shadow be = y
we have to calculate 
when x=4
from the similar triangles
we have,
or
Differentiating with respect to time 't' we get
or
Now for x = 4, and we have,
or
<u>here, the negative sign depicts the decrease in length and in the question it is asked the decreasing rate thus, the answer is </u><u>0.6375m/s</u>
Answer:
s = it+1/2 at²
s= 8×3+1/2 (10)(3)²
s = 24+45
s= 69
the object was thrown from a height of 69 meters
