Answer:
Explanation:
You need to look at this in 3 separate stages, and then sum thedistance from each stage:
Stage 1)
a=2
t=20
=0
We also need to find the final velocity
Stage 2)
a=0
v=40
t=20
Stage 3)
a=-3
=40
=0
So the total distance is
Sound waves.
Sound waves are not electromagnetic radiation. Every other option is an electromagnetic radiation.
Answer:
B.The force of friction between the block and surface will decrease.
Explanation:
The force of friction is given by
where is the coefficient of friction and is the normal force.
When the student pulls on the block with force at an angle , the normal force on the block becomes
and hence the frictional force becomes
.
Now, as we increase , increases which as a result decreases the normal force , which also means the frictional force decreases; Hence choice B stands true.
<em>P.S: Choice D is tempting but incorrect since the weight </em><em> is independent of the external forces on the block. </em>
as the surface area increases the rate of reaction also increases.
Explanation: