A/ S Level Mechanics

[kuiperbelt]

Please see link below:


https://ibb.co/nn2Nsc7

[bobbinwales]

do we use acc due to gravity as 10 or 9.8??

[bobbinwales]

i can google equations ..... so speed= sqaure root of 60 using g =10

[bobbinwales]

b) similar method square root 28??

[bobbinwales]

for c calculate time taken to reach ground then magnitude impulse = 0.4 x 10 (or 9.8) x time

Cant stop... back to counting how many pallet's of beans i can fit on the shelfs!

[ZebuSanctuary]

(a.) Using v² = u² + 2as where u is initial velocity = 0 m/s and taking 'a' due to gravity 10 m/s² (for ease of calculation & not 9.81 m/s²)

Rearranging for v = √2x10x3 = √60

v = 7.75 m/s

(b.) Again utilising v² = u² + 2as

Where the final velocity v = 0 m/s.
This is because the ball reaches its max height of 1.4 metres before wanting to return back to ground.

IMPORTANT TO NOTE:
Gravity is now acting against the direction of the initial velocity and will therefore be negative.

Thus 0² = u² + 2x(-10)x1.4 ---> 0² = u² - 28

Make u the subject ----> u² = 28 ----> u = √28

Initial velocity u = 5.29 m/s

(c.) Impulse = F x ▲t = ▲p where F is force in Newtons, ▲t is change in time and ▲p change in momentum.

Since no information is available regarding F and ▲t, then opt for momentum.

Impulse = ▲p = (final momentum - initial momentum)

Impulse = (mass x final velocity - mass x initial velocity)

I = (0.4 x 5.29 - 0.4 x (-7.75)

IMPORTANT -- Initial velocity (7.75) is negative because Impulse of the wall acting upon the impact of the ball is in the upwards direction, which is opposite to the direction of the ball's motion.

Moving on;

Answer -- Impulse = 5.22 kg m/s

(d.) Having calculated the Impulse and given the duration of the rebound i.e., 12/100 seconds;

I = F x ▲t ----> 5.22 = F x 0.12

Force = 43.5 N

Voila!

[bobbinwales]

Wow I got first 3 bits right! This A level stuff seems easier than all that circle gcse stuff you been posting kiperbelt

[bobbinwales]

Should say 1st 2 bits