Physics teacher guide grade 9

After landing on an unfamiliar planet, a space explorer constructs a simple pendulum of length 53.0 cm . The explorer finds that

larisa86 [58]

Answer:

12.4 m/s²

Explanation:

L = length of the simple pendulum = 53 cm = 0.53 m

n = Number of full swing cycles = 99.0

t = Total time taken = 128 s

T = Time period of the pendulum

g = magnitude of gravitational acceleration on the planet

Time period of the pendulum is given as

$T = \frac{t}{n}$

$T = \frac{128}{99}$

T = 1.3 sec

Time period of the pendulum is also given as

$T = 2\pi \sqrt{\frac{L}{g}}$

$1.3 = 2(3.14) \sqrt{\frac{0.53}{g}}$

g = 12.4 m/s²

4 0

3 years ago

Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. If there is no air resistance, when

Lelechka [254]

Answer:

option b

Explanation:

the heavier one will have twice the kinetic energy of the lighter one

5 0

3 years ago

3. An explosion of gas from a Hawaiian volcano blows a bunch of rocks into the sky. Each has 2000J of

anzhelika [568]

Answer: 3.906kg

Explanation:

K.E = 2000J

V = 32m/s

m =?

K.E = 1/2MV2

2000 = 1/2M x (32^2)

2000 = 1/2M x 1024

2000 = 512M

M = 2000/512

M = 3.906kg

4 0

3 years ago

One knife is longer from the cutting edge to the back of the blade. It's easier to push the longer knife through a pear and more

AlladinOne [14]

By the formula of torque balance we know that

$\tau = r\times F$

here we know that

r = distance of force

F = applied force

so here we know that as we will take large edge knife then the distance of force will increase

due to this the torque will also increase in it so it is easy to pear it

So here we can say

$F_{in}r_1 = F_{out}r_2$

$F_{out} = \frac{r_1}{r_2} F_{in}$

so output force will increase in this case

So here the correct answer would be

<em>b. the longer the knife, the stronger the output force</em>

6 0

3 years ago

. One long wire carries a current of 30 A along the entire x axis. A second-long wire carries a current of 40 A perpendicular to

d1i1m1o1n [39]

Answer:

magnitude of net magnetic field at given point is

$B = 5 \times 10^{-6} T$

Explanation:

As we know that magnetic field due to a long current carrying wire is given as

$B = \frac{\mu_o i}{2\pi r}$

here we we will find the magnetic field due to wire which is along x axis is given as

$i = 30 A$

r = 2 m

now we have

$B_1 = \frac{4\pi \times 10^{-7} (30)}{2\pi (2m)}$

$B_1 = 3\times 10^{-6} T$ into the plane

Now similarly magnetic field due to another wire which is perpendicular to xy plane is given as

$i = 40 A$

r = 2 m

now we have

$B_2 = \frac{4\pi \times 10^{-7} (40)}{2\pi (2m)}$

$B_2 = 4\times 10^{-6} T$ along + x direction

Since the two magnetic field is perpendicular to each other

So here net magnetic field is given as

$B = \sqrt{B_1^2 + B_2^2}$

$B = 5 \times 10^{-6} T$

5 0

3 years ago

Physics teacher guide grade 9​

Physics teacher guide grade 9