Question

particle moving with speed V = 10/2 ms - strikes a wall at an angle 45 as
shown in figure. Find magnitude of change in velocity.
a. 10/2 ms -1
b. Zero
c. 20 ms
d. 10 ms -1
W
isdom
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Answer 1

Given:

Particle moving at 10√2 m/s velocity strikes the wall at an angle of 45°.

To find:

Magnitude of change in velocity.

Calculation:

First refer to the attached diagram.

We can see that the change in velocity will occur only along the Y axis (i.e. along a direction perpendicular to the wall).

Let velocity be ∆v.

$\sf{ \therefore \: \Delta v = v \cos( \theta) - \{- v \cos( \theta) \}}$

$\sf{ = > \: \Delta v = 2v \cos( \theta) }$

$\sf{ = > \: \Delta v = 2v \cos( 90 \degree - 45 \degree) }$

$\sf{ = > \: \Delta v = 2v \cos(45 \degree) }$

$\sf{ = > \: \Delta v = 2 \times 10 \sqrt{2} \times \cos(45 \degree) }$

$\sf{ = > \: \Delta v = 2 \times 10 \sqrt{2} \times \dfrac{1}{ \sqrt{2} } }$

$\sf{ = > \: \Delta v = 2 \times 10 }$

$\sf{ = > \: \Delta v = 20 \: m {s}^{ - 1} }$

So, final answer is :

$\boxed{ \red{ \bold{ \large{\: \Delta v = 20 \: m {s}^{ - 1} }}}}$

Answer 2

Answer: C)20m/sec

Explanation: