Question

@Abhisar

The diagram shows a 0.74-kg square block at four positions along a track. The track is frictionless between points A and B. Elsewhere, the coefficient of static friction on the block is 0.36.

Initially, the block is held in place against a spring by a horizontal external force of magnitude 29 N. Then the external force is removed, and the block is projected forward with speed . The block descends a ramp and has speed at the bottom. At point C, its speed is . The block stops at point D.

What is the initial compression of the spring?

Answer 1

Answers
What is the initial compression of the spring?

7.3 cm
9.2 cm
2.0 cm
3.7 cm
5.5 cm

Answer 2

V1=1.2m/s
V2=1.9m/s
V3=1.4m/s

Answer 3

https://patr1234-patr-pps.gradpoint.com/Resource/4332114,5F1,0,0,0,0,0/Assets/testitemimages/physics_a/work_and_energy/phynofor-f120g1_r.jpg

Diagram

Answer 4

@Abhisar
Can u help

Answer 5

The velocities are given and the only thing to find out is compression in the spring. right ?

Answer 6

Yes

Answer 7

What is the (kinetic) energy of the block when it is projected ?

Answer 8

29 n

Answer 9

No! That is the force which compresses the spring.

Answer 10

10.44 I did .36*29

Answer 11

No! I am asking kinetic energy when the block is projected. Don't consider that track with friction now.

Answer 12

I did mass times velocity squared times .5 and got .5328. Not sure how else to solve

Answer 13

Ok. That's correct. Let's use symbols for mass and velocity. Once we get the final result, we shall plug in the given numerical values.

Answer 14

Let the mass of the block be m. Then kinetic energy of the when it is released is \(mv_1 ^2 / 2\)

Answer 15

Where does the block gain this energy from ?

Answer 16

The spring compressed

Answer 17

Yes

Answer 18

What is the energy of spring compression ?

Answer 19

The .5328

Answer 20

Is there any formula to find spring energy ?

Answer 21

.5*k*s^2

Answer 22

Correct! But s in the diagram represents the length of the track with friction. Let's say x is the initial compression. Then spring energy is .5*k*x^2.
What is relationship between the restoring force and the spring constant ?

Answer 23

They r equal. What is the value of k

Answer 24

Restoring force, F = -kx
So, spring energy = \(0.5\times |F| \times x\)
Right ?

Answer 25

Right is f the .5328

Answer 26

F is 29 newton. Now plug in the values and find x.

Answer 27

So x 14.5 bc .5*29

Answer 28

14.5 isn't an answer though

Answer 29

x should be 0.0367 meter

Answer 30

Thanks