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>
Answer:
Explanation:
<u>1. Name of the variables:</u>

<u>2. Formulae:</u>




<u>3. Solution (calculations)</u>




Answer:
Velocity of airplane is 500 km/h
Velocity of wind is 40 km/h
Explanation:
= Velocity of airplane in still air
= Velocity of wind
Time taken by plane to travel 1150 km against the wind is 2.5 hours

Time taken by plane to travel 450 km against the wind is 50 minutes = 50/60 hours

Subtracting the two equations we get

Applying the value of velocity of wind to the first equation

∴ Velocity of airplane in still air is 500 km/h and Velocity of wind is 40 km/h
Answer:
A wave is a vibration in mediun tbat carries energy from one place to another.
Explanation:
Answer:
Yes! Light from the sun can affect the materials certain carpets are made out of. The usual effect being the dye in the carpet being "washed out" or "dried out" as the sun beams down on it. When this happens, the carpet will usually lose its color, causing it to fade.