Dynamics of material (momentum )

[Faraz]

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >

Hi, I am having difficulty solving the problem, please resolve it if possible. my work and the image for the problem is attached. Thanks
The 10 kg block is at rest on the bottom of the incline (θ = 30°) when it is suddenly struck by a 50 kN force that sends it sliding up the incline. The duration of the force is 5 ms and the coefficient of kinetic friction between the block and the incline is 0.2. The block slides 30 m up the incline and makes contact with the spring (initially uncompressed, k = 15 kN/m). What is the maximum compression of the spring

 

[ehild]

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >

Hi, I am having difficulty solving the problem, please resolve it if possible. my work and the image for the problem is attached. Thanks
The 10 kg block is at rest on the bottom of the incline (θ = 30°) when it is suddenly struck by a 50 kN force that sends it sliding up the incline. The duration of the force is 5 ms and the coefficient of kinetic friction between the block and the incline is 0.2. The block slides 30 m up the incline and makes contact with the spring (initially uncompressed, k = 15 kN/m). What is the maximum compression of the spring
View attachment 97539

View attachment 97540 View attachment 97537

You solved a different problem. What does the 50 kN force do with the 10 kg block in 5 ms?

 

[Faraz]

i KNOW i should use conservation of momentum but don't know how

 

[ehild]

i KNOW i should use conservation of momentum but don't know how

Momentum is conserved if no force acts on the body.
There are forces acting on the 10 kg block. It is in rest initially. Does it stay in rest when the force acts on it ?

 

[Faraz]

no

 

[Faraz]

so why is the time given

 

[Faraz]

im really confused, because in that case my solution is correct

 

[ehild]

Will it move? with what velocity?

 

[ehild]

so why is the time given

In what case?

 

[Faraz]

did you check out the attachments?

 

[ehild]

did you check out the attachments?

Yes. It is wrong. You did not you use the given force and time, what you did is not related to the problem.
Read the problem statement carefully.

 

[Faraz]

ive done it numerous times, can you actually help me solve it

 

[ehild]

ive done it numerous times, can you actually help me solve it

I tried to help you, but you said that you solved the problem correctly.
I ask again: what happens to a body if force is applied to it?

 

[Faraz]

it moves

 

[ehild]

it moves

Imagine the setup. There is a block in rest at the bottom of a slope. Far away from it, there is a spring at the top of the slope. How can the block compress the spring? It has to reach it. For that , it needs enough velocity. How does it get velocity? If force is applied to it.
It accelerates, gains some velocity and momentum during some time.
How is the change of momentum related to the force and time of application of the force?

 

[Faraz]

impulse?

 

[ehild]

impulse?

Yes, impulse. What impulse does the block get if 50 kN force is applied for 5ms?

 

[Faraz]

ft

 

[ehild]

How much is it? and what velocity does the block gain from that impulse?

 

[Faraz]

 

[Faraz]

i just resolved it, is it correct?

 

[ehild]

I can not read your handwriting. Explain what you do.