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aleksandr82 [10.1K]

3 years ago

8

Consider a situation where a constant force of 25 N acts on an object having a mass of 2 kg for 3 seconds. What is the work done

by the force

1 answer:

blagie [28]3 years ago

3 0

Answer:

Work done W =1406.25 J

Explanation:

Work done on a body can be calculated using newton's 2nd laws:

F=ma

$\Rightarrow a=\frac{F}{m}$

Hence acceleration of the block is given by:

$\Rightarrow a=\frac{25}{2}=12.5m/s^2$

Displacement of the object is given by:

$\Rightarrow S=ut+\frac{1}{2}at^2$

Substitute the values

$\Rightarrow S=0*3+\frac{1}{2}(12.5)3^2$

$\Rightarrow S=56.25 m$

Now work done is given by:

W=F.S

W = 25×56.25

W =1406.25 J

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The benefits of jumping rope include: (which of these things)

Svetach [21]

Answer:

E. All of the Above

Explanation:

By doing any kind of exercise or physical activity, you are increasing your overall health. Your muscle strengthen because of the jumping and movement of arms. You are more alert because you have to time each jump right in order to keep going. By breathing evenly while jumping, you do help your Cardiorespiratory fitness as well. And of course, you increase your athletic ablility over all with much endurance and practice.

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3 years ago

You and your friend are pushes hard against a stationary wall. If you push 3 times harder than your friend, then the amount of w

shtirl [24]

Answer:

Work = F * s where s is the distance F moves

Since F is stationary, in this case, "no work" is done by either person

5 0

2 years ago

Radio waves transmitted through space at 3.00 ✕ 108 m/s by the Voyager spacecraft have a wavelength of 0.137 m. What is their fr

fredd [130]

Answer:

Frequency, $f=2.18\times 10^9\ Hz$

Explanation:

We have,

Speed of radio waves is $3\times 10^8\ m/s$

Wavelength of radio waves is $\lambda=0.137\ m$

It is required to find the frequency of the radio waves. The speed of a wave is given by :

$v=f\lambda\\\\f=\dfrac{v}{\lambda}\\\\f=\dfrac{3\times 10^8}{0.137}\\\\f=2.18\times 10^9\ Hz$

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8 0

3 years ago

A record turntable rotates through 5.0 rad in 2.8 s as it is accelerated uniformly from rest. What is the angular velocity at th

Usimov [2.4K]

Answer:

$\omega_f = 3.584\ rad/s$

Explanation:

given,

turntable rotate to, θ = 5 rad

time, t = 2.8 s

initial angular speed = 0 rad/s

final angular speed = ?

now, using equation of rotational motion

$\theta = \omega_i t + \dfrac{1}{2}\alpha t^2$

$5 = 0+ \dfrac{1}{2}\alpha\times 2.8^2$

$\alpha= \dfrac{10}{2.8^2}$

α = 1.28 rad/s²

now, calculation of angular velocity

$\omega_f = \omega_i + \alpha t$

$\omega_f =0 +1.28\times 2.8$

$\omega_f = 3.584\ rad/s$

hence, the angular velocity at the end is equal to 3.584 rad/s

4 0

3 years ago

During a neighborhood baseball game in a vacant lot, a particularly wild hit sends a 0.146 kg baseball crashing through the pane

Nonamiya [84]

Answer:

Impulse, |J| = 0.6716 kg-m/s

Force, F = 63.35 N

Explanation:

It is given that,

Mass of the baseball, m = 0.146 kg

Initial speed of the ball, u = 15.3 m/s

Final speed of the ball, v = 10.7 m/s

To find,

(a) The magnitude of this impulse.

(b) The magnitude of the average force of the glass on the ball.

Solution,

(a) Impulse of an object is equal to the change in its momentum. It is given by :

$J=m(v-u)$

$J=0.146\ kg(10.7-15.3)\ m/s$

J = -0.6716 kg-m/s

or

|J| = 0.6716 kg-m/s

(b) Another definition of impulse is given by the product of force and time of contact.

t = 0.0106 s

$J=F\times \Delta t$

$F=\dfrac{J}{\Delta t}$

$F=\dfrac{0.6716\ kg-m/s}{0.0106\ s}$

F = 63.35 N

Hence, this is the required solution.

6 0

3 years ago