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4 years ago

Which force acts during projectile motion? A. Nuclear force B. Electric force C. Gravity D. Magnetic force

Physics

1 answer:

Mademuasel [1]4 years ago

6 0

Option (C) is correct.

A projectile is an object launched at an angle with the horizontal and allowed to move freely under the effect of gravity alone.

Thus the only external force acting on a projectile is the force of gravity.There may be the force of air friction acting but for all practical purposes, we neglect its effect.

Thus only force of gravity acts during projectile motion.

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How do the forces acting on a boat compare to the force acting on a plane ?

erica [24]

Answer:

on there boat there will two main forces act 1,upthrust which comes from water and air and other side on the plane air and gravity.

Explanation:

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3 years ago

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If a net force of 250 N causes an object to accelerate at 20m/s^2 what must its mass be?

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4 years ago

Steam is to be condensed on the shell side of a heat exchanger at 150 oF. Cooling water enters the tubes at 60 oF at a rate of 4

zalisa [80]

Answer:

a. 572Btu/s

b.0.1483Btu/s.R

Explanation:

a.Assume a steady state operation, KE and PE are both neglected and fluids properties are constant.

From table A-3E, the specific heat of water is $c_p=1.0\ Btu/lbm.F$ , and the steam properties as, A-4E:

$h_{fg}=1007.8Btu/lbm, s_{fg}=1.6529Btu/lbm.R$

Using the energy balance for the system:

$\dot E_{in}-\dot E_{out}=\bigtriangleup \dot E_{sys}=0\\\\\dot E_{in}=\dot E_{out}\\\\\dot Q_{in}+\dot m_{cw}h_1=\dot m_{cw}h_2\\\\\dot Q_{in}=\dot m_{cw}c_p(T_{out}-T_{in})\\\\\dot Q_{in}=44\times 1.0\times (73-60)=572\ Btu/s$

Hence, the rate of heat transfer in the heat exchanger is 572Btu/s

b. Heat gained by the water is equal to the heat lost by the condensing steam.

-The rate of steam condensation is expressed as:

$\dot m_{steam}=\frac{\dot Q}{h_{fg}}\\\\\dot m_{steam}=\frac{572}{1007.8}=0.5676lbm/s$

Entropy generation in the heat exchanger could be defined using the entropy balance on the system:

$\dot S_{in}-\dot S_{out}+\dot S_{gen}=\bigtriangleup \dot S_{sys}\\\\\dot m_1s_1+\dot m_3s_3-\dot m_2s_2-\dot m_4s_4+\dot S_{gen}=0\\\\\dot m_ws_1+\dot m_ss_3-\dot m_ws_2-\dot m_ss_4+\dot S_{gen}=0\\\\\dot S_{gen}=\dot m_w(s_2-s_1)+\dot m_s(s_4-s_3)\\\\\dot S_{gen}=\dot m c_p \ In(\frac{T_2}{T_1})-\dot m_ss_{fg}\\\\\\\dot S_{gen}=4.4\times 1.0\times \ In( {73+460)/(60+460)}-0.5676\times 1.6529\\\\=0.1483\ Btu/s.R$

Hence,the rate of entropy generation in the heat exchanger. is 0.1483Btu/s.R

4 0

4 years ago

Five multiple choice science questions! Help please!

andreyandreev [35.5K]

1) the sun (greek name Helios gives heliocentric)
2) A. Newton's laws of motion can prove this as well as Kepler's Laws
3) D. Inertia keeps it from falling onto the sun and gravity keeps it from going off in a straight line
4) moons. They orbit planets not suns directly
5) B (International Space Station gives a hint)

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4 years ago