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2 years ago

A parent pushes a stroller with a 11.2 N force for 15.9 m. How much work did the parent do?

1 answer:

7 0

The definition of work is that it is the Force applied over a distance, times the distance. The only trick is that you have to account only for forces in the direction of movement; any forces that are normal to the movement are not taken into account. Intuitively, work is generated only by forces that contribute to the movement (or go against it; same or opposite direction).

Let us see now: W=F*d =11.2N* 15.9m=178.1 N*m=178.1 J where J stands for Joules. This is the work that the parent did, namely how much energy he had to put in to move the stroller.

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Every spring has an equilibrium position. Which statements describe a spring at its equilibrium position? Check all that

alexgriva [62]

Answer:

The elastic potential energy is zero.

The net force acting on the spring is zero.

Explanation:

The equilibrium position of a spring is the position that the spring has when its neither compressed nor stretched - it is also called natural length of the spring.

Let's now analyze the different statements:

The spring constant is zero. --> false. The spring constant is never zero.

The elastic potential energy is at a maximum --> false. The elastic potential energy of a spring is given by

$E=\frac{1}{2}kx^2$

where k is the spring constant and x the displacement. Therefore, the elastic potential energy is maximum when x, the displacement, is maximum.

The elastic potential energy is zero. --> true. As we saw from the equation above, the elastic potential energy is zero when the displacement is zero (at the equilibrium position).

The displacement of the spring is at a maxi num --> false, for what we said above

The net force acting on the spring is zero. --> true, as the spring is neither compressed nor stretched

8 0

2 years ago

Read 2 more answers

At room temperature, a typical person loses energy to the surroundings at the rate of 62 W. If this energy loss has to be made u

Alex_Xolod [135]

To solve this problem it is necessary to use the given proportions of power and energy, as well as the energy conversion factor in Jules to Calories.

The power is defined as the amount of energy lost per second and whose unit is Watt. Therefore the energy loss rate given in seconds was

$P = \frac{E}{t} \rightarrow E= Energy, t = time$

$P = 62W = 62 \frac{J}{s}$

The rate of energy loss per day would then be,

$P = 62\frac{J}{s} (\frac{86400s}{1day})$

$P = 5356800 \frac{J}{day}$

That is to say that Energy in Jules per lost day is 5356800J

By definition we know that $1KCal = 4.184*10^{6}J$

In this way the energy in Cal is,

$E = 5356800J \frac{1KCal}{4.184*10^{6}J}$

$E = 1279.694 KCal$

The number of kilocalories (food calories) must be 1279.694 KCal

4 0

2 years ago

An electric ceiling fan is rotating about a fixed axis with an initial angular velocity magnitude of 0.240 rev/s. The magnitude

bazaltina [42]

Explanation:

Given that,

Angular velocity = 0.240 rev/s

Angular acceleration = 0.917 rev/s²

Diameter = 0.720 m

(a). We need to calculate the angular velocity after time 0.203 s

Using equation of angular motion

$\omega_{f}=\omega_{i}+\alpha t$

Put the value in the equation

$\omega_{f}=0.240+0.917\times0.203$

$\omega_{f}=0.426\ rev/s$

The angular velocity is 0.426 rev/s.

(b). We need to calculate the tangential speed of the blade

Using formula of tangential speed

$v= r\omega$

Put the value into the formula

$v = \dfrac{0.720 }{2}\times0.426\times2\pi$

$v=0.963\ m/s$

The tangential speed of the blade is 0.963 m/s.

(c). We need to calculate the magnitude at of the tangential acceleration

Using formula of tangential acceleration

$a_{t}=r\alpha$

Put the value into the formula

$a_{t}=0.36\times0.917\times2\pi$

$a_{c}=2.074\ m/s^2$

The tangential acceleration is 2.074 m/s².

Hence, This is required solution.

4 0

2 years ago

When the wind kicks up dust and sand, the dust grains are charged. The small grains tend to get a negative charge, and the large

diamong [38]

Answer:

Explanation:

Small grains are negatively charged by the wind while big grains is positively charged and remains at the ground . This process creates an electric field due to the presence of oppositely charged particles.

When ever electric field exists it is directed from a positive charge to a negative charge so the here electric field is towards an upwards direction.

4 0

2 years ago

An electron and a proton, starting from rest, are accelerated through an electric potential difference of the same magnitude. in

Yakvenalex [24]

The charges are the same in absolute value, so the change of potential energy is the same. That means that the change in kinetic energy is also the same. Then:

1 = Ke/Kp = m_e *v_e^2 / m_p * v_p^2, or

v_e/v_p = sqrt( m_p/m_e),

So the speed of the electron will be sqrt( m_p/m_e) times greater than the speed of the proton

4 0

2 years ago