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4 years ago

A grade 12 Physics student shoots a basketball

Physics

1 answer:

Nadusha1986 [10]4 years ago

6 0

Answer:

7.84 m/s

Explanation:

Height, h = 2 m

Initial velocity, u = 10 m/s

Angle, A = 80°

(a) Let the time taken to go to the net is t.

Use second equation of motion

$h = u t + 0.5 at^2\\\\- 2 = - 10 sin 80 t - 4.9 t^2\\\\4.9 t^2 + 9.8 t - 2 = 0 \\\\t= \frac{- 9.8\pm\sqrt{9.8^2 + 4\times 4.9\times 2}}{9.8}\\\\t = \frac{- 9.8 \pm 11.6}{9.8}\\\\t = - 2.2 s , 0.2 s$

Time cannot be negative.

So, t = 0.2 s

The vertical velocity at t = 0.2 s is

v = u + at

v = 10 sin 80 - 9.8 x0.2

v = 9.8 - 1.96 = 7.84 m/s

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A 75.0-kg person is riding in a car moving at 20.0 m/s when the car runs into a bridge abutment. (a) calculate the average force

iragen [17]

(a) $-1.5\cdot 10^6 N$

First of all, we need to calculate the acceleration of the person, by using the following SUVAT equation:

$v^2 -u ^2 = 2ad$

where

v = 0 is the final velocity

u = 20.0 m/s is the initial velocity

a is the acceleration

d = 1.00 cm = 0.01 m is the displacement of the person

Solving for a,

$a=\frac{v^2-u^2}{2d}=\frac{0-20.0^2}{2(0.01)}=-20000 m/s^2$

And the average force on the person is given by

$F=ma$

with m = 75.0 kg being the mass of the person. Substituting,

$F=(75)(-20000)=-1.5\cdot 10^6 N$

where the negative sign means the force is opposite to the direction of motion of the person.

b) $-1.0\cdot 10^5 N$

In this case,

v = 0 is the final velocity

u = 20.0 m/s is the initial velocity

a is the acceleration

d = 15.00 cm = 0.15 m is the displacement of the person with the air bag

So the acceleration is

$a=\frac{v^2-u^2}{2d}=\frac{0-20.0^2}{2(0.15)}=-1333 m/s^2$

So the average force on the person is

$F=ma=(75)(-1333)=-1.0\cdot 10^5 N$

7 0

4 years ago

A light source of wavelength \lambdaλ illuminates a metal with a work function of \text{BE} = 2.00 ~\text{eV}BE=2.00 eV and ejec

dsp73

Answer:

1 eV

Explanation:

Given:

Work function, ∅ = 2.00 eV

Kinetic energy of the ejected of the electron, K.E = 4.0 eV

Now,

using the photoelectric equation , we have

Energy of the photon (E) = ∅ + K.E

also,

E = hc/λ

where, h is plank's constant

c is the speed of the light

λ is the wavelength

thus, we have

hc/λ = 2 + 4 = 6 eV

Energy of photon = 6eV

Now,

for the second case

λ' = 2λ

when Wavelength is doubled , E is halved

thus,

E' = hc/λ'

E' = hc/2λ

E' = E/2 = 6/2 = 3 eV

also,

E' = ∅ + KE '

thus on substituting the values,

3 = 2 + KE'

KE' = 1 eV

Hence, the maximum kinetic energy for the second case is 1 eV

5 0

3 years ago

According to Newton's Brd Law, an object's momentum depends on it's velocity and mass, 4 dog-sled teams

Kryger [21]

Answer:

Team A has the greatest momentum

Explanation:

The momentum of an object is a vector quantity given by

$p=mv$

where

m is the mass of the object

v is its velocity

In this problem, we have to compare the momenta of the different sleds.

We have:

A) Sled Team A 48 kg moving at 10m/s:

m = 48 kg

v = 10 m/s

p = (48)(10) = 480 kg m/s

B) Sled Team B 14 kg moving at 18m/s

m = 14 kg

v = 18 m/s

p = (14)(18) = 252 kg m/s

C) Sled Team C 28 kg moving at 12m/s

m = 28 kg

v = 12 m/s

p = (28)(12) = 336 kg m/s

D) Sled Team D 22 kg moving at 12m/s

m = 22 kg

v = 12 m/s

p = (22)(12) = 264 kg m/s

So, team A has the greatest momentum.

4 0

3 years ago

Mae prefers to complete graphs or charts to show the information she has learned. What kind of learner is Mae likely to be?

yan [13]

Answer:

Prob. D

Explanation:

I am also a Visual Learner.

3 0

3 years ago

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Number of atoms present in 1 mole of oxygen atom

Afina-wow [57]

Answer:

1 mole of every substance has 6.022 × 10^23 particles. This is called Avagadro's constant

3 0

4 years ago