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2 years ago

An 8 kg toddler is running at a speed of 10 m/s. how much energy does he have?

1 answer:

8 0

To find the Kinetic energy this is the equation

KE=1/2mv^2

so we know the mass (m) which is 8kg

we also know the velocity (v) which is 10 m/s

so we plug that into the equation and it should look like this - 1/2(8kg)(10m/s)^2 now we solve

so 1/2 x 8 = 4 so then we just do (4)(10)^2 which gets us 400.

Since kinetic=Joules

The answer is 400 J

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A student lifts a set of books off a table and places them in the upper shelf of a book case which is 2 meters above the table.

AfilCa [17]

The work done is the product between the intensity of the force applied F, the amount of the displacement d of the book and the cosine of the angle $\theta$ between the direction of the force and the direction of the displacement:
$W=Fd \cos \theta$
In our problem, the student is lifting the book, so he is applying a force directed upward, and the book is moving upward, so F and d are parallel and therefore the angle is zero, so $\cos \theta = \cos 0=1$
Therefore, the work done is
$W=Fd=(5 N)(2 m)=10 J$

6 0

2 years ago

Read 2 more answers

In the produce section of a supermarket, five pears are placed on a spring scale. The placement of the pears stretches the sprin

tankabanditka [31]

Answer:

The displacement of the spring due to weight is 0.043 m

Explanation:

Given :

Mass $m = 2$ Kg

Spring constant $k = 450 \frac{N}{m}$

According to the hooke's law,

$F = -kx$

Where $F =$ force, $x =$ displacement

Here,

$F = mg$ ( $g = 9.8 \frac{m}{s^{2} }$ )

$F = 2 \times 9.8 = 19.6$ N

Now for finding displacement,

$x = \frac{F}{k}$

Here minus sign only represent the direction so we take magnitude of it.

$x = \frac{19.6}{450}$

$x = 0.043$ m

Therefore, the displacement of the spring due to weight is 0.043 m

8 0

2 years ago

A small glass bead charged to 8.0 nC is in the plane that bisects a thin, uniformly charged, 10-cm long glass rod and is 4.0 cm

Assoli18 [71]

Answer:

71nC is the total charge of the rod

Explanation:

See attached file

8 0

2 years ago

A 50 kg rocket generates 990 N of thrust. What will be its acceleration if it is launched straight up?

Ilia_Sergeevich [38]

Answer:

The acceleration of the rocket is 10 m/s².

Explanation:

Let the acceleration of the rocket be $a$ m/s².

Given:

Mass of the rocket is, $m=50\ kg$

Thrust force acting upward is, $F_{th}=990\ N$

Acceleration due to gravity is, $g=9.8\ m/s^2$

Now, force acting in the downward direction is due to the weight of the rocket and is given as:

$W=mg=50\times 9.8=490\ N$

Now, net force acting on the rocket in upward direction is given as:

$F_{net}=F_{th}-W\\F_{net}=990-490=500\ N$

Therefore, from Newton's second law, net force acting on the rocket is equal to the product of mass and acceleration.

$F_{net}=ma\\500=50a\\a=\frac{500}{50}=10\ m/s^2$

Therefore, the acceleration of the rocket is 10 m/s².

4 0

2 years ago

Geoff counts the number of oscillations of a simple pendulum at a location where the acceleration due to gravity is 9.80 m/s2, a

loris [4]

Period of a simple pendulum = 2π √(L/G)

(25 sec/15) = 2π √(L / 9.8 m/s²)

5/3 sec = 2π √(L/9.8 m/s²)

5 sec / 6π = √ (L/9.8 m/s²)

(5sec · √9.8m/s²) / 6π = √L

Square each side:

(25 s²) · (9.8 m/s²) / 36π² = L

L = (25 · 9.8) / (36 π²) meters

L = 0.69 meter

7 0

2 years ago