PHYSICS COLLEGE

Two ice skaters, Lilly and John, face each other while at rest, and then push against each other's hands. The mass of John is twice that of Lilly. How do their speeds compare after they push off? Lilly's speed is one-fourth of John's speed. Lilly's speed is the same as John's speed. Lilly's speed is two times John's speed. Lilly's speed is four times John's speed. Lilly's speed is one-half of John's speed.

Answers

Answer 1

Answer:

Answer:

Lilly's speed is two times John's speed.

Explanation:

m = Mass

a = Acceleration

t = Time taken

u = Initial velocity

v = Final velocity

The force they apply on each other will be equal

$F=ma\n\Rightarrow a_l=(F)/(m_l)$

$F=ma\n\Rightarrow a_j=(F)/(2m_l)\n\Rightarrow a_j=(1)/(2)a_l$

$v=u+at\n\Rightarrow v_l=0+(F)/(m_l)* t\n\Rightarrow v_l=a_lt$

$v=u+at\n\Rightarrow v_l=0+(F)/(2m_l)* t\n\Rightarrow v_j=(1)/(2)a_lt\n\Rightarrow v_j=(1)/(2)v_l\n\Rightarrow v_l=2v_j$

Hence, Lilly's speed is two times John's speed.

Answer 2

Answer:

Answer:

Lilly's speed is 2 times Johns speed

Explanation:

Related Questions

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A parallel-plate capacitor is charged and then disconnected from the battery. By what factor does the stored energy change when the plate separation is then doubled?
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As a delivery truck travels along a level stretch of road with constant speed, most of the power developed by the engine is used to compensate for the energy transformations due to friction forces exerted on the delivery truck by the air and the road. If the power developed by the engine is 2.43 hp, calculate the total friction force acting on the delivery truck (in N) when it is moving at a speed of 24 m/s. One horsepower equals 746 W.
(25) A grinding machine is supported on an isolator that has two springs, each with stiffness of k and one viscous damper with damping constant of c=1.8 kNs/m. The floor on which the machine is mounted is subjected to a harmonic disturbance due to the operation of an unbalanced engine in the vicinity of the grinding machine. The floor oscillates with amplitude Y=3 mm and frequency of 18 Hz. Because of other design constraints, the stiffness of each spring must be greater than 3.25 MN/m. What is the minimum required stiffness of each of the two springs to limit the grinding machine’s steady-state amplitude of oscillation to at most 10 mm? Assume that the grinding machine and the wheel are a rigid body of weight 4200 N and can move in only the vertical direction (the springs deflect the same amount).

While doing her crossfit workout, Yasmeen holds an 7.0 kg weight at arm's length, a distance of 0.57 m from her shoulder joint. What is the torque about her shoulder joint due to the weight if her arm is horizontal? A 30 N m B. 4.0 N m C. 43N-m D. 39 N m

Answers

Answer:

D. 39 N m

Explanation:

m = mass of the weight used in crossfit workout = 7.0 kg

Force due to the weight used is given as

F = mg

F = (7.0) (9.8)

F = 68.6 N

d = distance of point of action of weight from shoulder joint = 0.57 m

τ = Torque about the shoulder joint due to the weight

Torque about the shoulder joint due to the weight is given as

τ = F d

Inserting the values

τ = (68.6) (0.57)

τ = 39 Nm

A 1.5m wire carries a 7 A current when a potential difference of 87 V is applied. What is the resistance of the wire?

Answers

Answer:

$R\approx12.43 \,\, \Omega$

Explanation:

We can use Ohm's Law to find the resistance R of a wire that carries a current I under a given potential difference:

$V=I\,\,R\nR = (V)/(I) \nR=(87)/(7) \nR\approx12.43 \,\, \Omega$

Answer:

Ohm's law states that I=V/R (Current=volts divided by resistance). Since we're looking for resistance, we'll rewrite it as R=V/I. Then just plug in the numbers; R=84/9, R= 9 1/3 or 28/3. The resistance of the wire is 9.33... or 9 1/3 ohm's, depending on how you wanna write it.

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Explain how ultrasound devices use the Doppler effect to create images of body parts. HELP ME ASAP!! Will give brainliest answer!!

Answers

Answer:

Transmits high-frequency (1 to 5 megahertz) sound pulses into your body using a probe. The sound waves travel into your body and hit a boundary between tissues (e.g. between fluid and soft tissue, soft tissue and bone).

Explanation:

Doppler ultrasound works by measuring sound waves that are reflected from moving objects, such as red blood cells.

Answer:

The guy above is pretty good

Explanation:

I'd go with that answer, give them brainliest

If the radio waves transmitted by a radio station have a frequency of 83.5 MHz, what is the wavelength of the waves, in meters

Answers

Answer: wavelength =3.52m

Explanation:

,λ=c/μ

where c=speed of the light,λ=wave length, μ=frequncy

c=3x10^8m/s

And

μ=83.5/MHz =85.3x10^6Hz==85.3x10^6Hz=

=85.3x10^6s-1

λ=c/μ

=3x10^8m/s/85.3x10^6s-1

=3.51699883

=3.52m

We can calculate the force that the atmospheric pressure produces on a surface. Consider a living room that has a 4.0m×5.0m floor and a ceiling 3.0m high. What is the total force on the floor due to the air above the surface if the air pressure is 1.00 atm?

Answers

Answer:

Force, $F=2.02* 10^6\ N$

Explanation:

It is given that,

Length of the room, l = 4 m

breadth of the room, b = 5 m

Height of the room, h = 3 m

Atmospheric pressure, $P=1\ atm=101325\ Pa$

We know that the force acting per unit area is called pressure exerted. Its formula is given by :

$P=(F)/(A)$

$F=P* l* b$

$F=101325* 4* 5$

$F=2.02* 10^6\ N$

So, the total force on the floor due to the air above the surface is $2.02* 10^6\ N$ . Hence, this is the required solution.

Nitrogen (N2) undergoes an internally reversible process from 6 bar, 247°C during which pν1.2 = constant. The initial volume is 0.1 m3 and the work for the process is 50 kJ. Assuming ideal gas behavior, and neglecting kinetic and potential energy effects, determine heat transfer, in kJ, and the entropy change, in kJ/K.

Answers

Answer:

$Q=25\ kJ$

$\Delta s= 0.2885 J.K^(-1)$

Explanation:

Given:

Initial pressure of nitrogen, $P_1=6* 10^5\ Pa$

initial temperature, $T_1=247+273=520\ K$

polytropic index, $n=1.2$

initial volume, $V_1=0.1\ m^3$

work done in the process, $W=50000\ J$

For heat interaction during the polytropic process we have:

$Q=W[(\gamma -n)/(\gamma-1) ]$

$Q=50*[(1.4-1.2)/(1.4-1) ]$

$Q=25\ kJ$

For ideal gas we have the Gas Law:

$P_1.V_1=m.R.T_1$

$6* 10^5* 0.1=m.R* 520$

$m.R=115.385\ J.K^(-1)$

For work we have the relation:

$W=m.R.((T_1-T_2))/((n-1))$

putting respective values

$50000=115.385* ((520-T_2))/((1.2-1))$

$T_2=433.33\ K$

We know entropy change:

$\Delta s=(dQ)/(dT)$

$\Delta s=(25)/(520-433.33)$

$\Delta s= 0.2885 J.K^(-1)$

Final answer:

The given question involves the thermodynamic process of an internally reversible process of nitrogen gas (N2) at specific pressure and temperature with a constant value of pν1.2. However, the question does not provide enough information to calculate the heat transfer and entropy change accurately.

Explanation:

The given question involves the thermodynamic process of an internally reversible process of nitrogen gas (N2) at specific pressure and temperature with a constant value of pν1.2. In order to determine the heat transfer and entropy change, we need to use the first and second laws of thermodynamics. However, the question does not provide enough information to calculate the heat transfer and entropy change accurately.

Learn more about thermodynamic process here:

brainly.com/question/31237212

#SPJ12

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