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elixir [45]
3 years ago
7

You need to push a heavy box across a rough floor, and you want to minimize the average force applied to the box during the time

the box is being pushed. Which method of pushing results in the minimum average force being applied to the box?
A. Keep pushing the box forward at a steady speed.
B. Push the box forward a short distance, rest, then repeat until finished,
C. Push the box so that it accelerates forward at a constant rate.
Physics
1 answer:
Lemur [1.5K]3 years ago
4 0

Answer:A. Keep pushing the box forward at a steady speed.

Explanation: Frictional force is a resistant force which oppose the Movement of an object, frictional force can emanate from a rough surface.

When an object that is moving with a consistent force is opposed by the roughness of the surface through which it is moving,it will cause the object to continue to move with a reduced speed as it goes along.

WHEN YOU APPLY A CONSTANT FORCE ON A MOVING OBJECT THAT IS OPPOSED BY A ROUGH SURFACE IT WILL RESULT IN AN AVERAGE MINIMAL FORCE BEING APPLIED TO THE OBJECT.

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Answer:

The field gets weaker

Explanation:

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What is kinetic energy of a 7.26kg bowling ball that is rolling at a speed of 2m/s?
sergey [27]

Kinetic energy is the energy possessed by an object when that object is moving in space. The higher the mass of an object or higher the speed of an object the higher the kinetic energy will be.

So to calculate the Kinetic Energy we can use the following formula

K.E=(1/2)*m*v^2

Inserting the values in formula gives:

K.E=1/2*7.26*2^2

14.52J

This is the final answer which gives the kinetic energy of the ball.

8 0
3 years ago
Calculate the amount of heat needed to raise the temperature of 200g of ice from-30°C 50C water. (C = .5 for ice, C 1 for water,
Nitella [24]

<u>Answer:</u> The amount of heat needed is 29000 Cal.

<u>Explanation:</u>

The process involved in this problem are:

(1):H_2O(s)(-30^oC)\rightarrow H_2O(s)(0^oC)\\\\(2):H_2O(s)(0^oC)\rightarrow H_2O(l)(0^oC)\\\\(3):H_2O(l)(0^oC)\rightarrow H_2O(l)(50^oC)

Now, we calculate the amount of heat released or absorbed in all the processes.

  • <u>For process 1:</u>

q_1=mC_{p,s}\times (T_2-T_1)

where,

q_1 = amount of heat absorbed = ?

m = mass of ice = 200 g

T_2 = final temperature = 0^oC

T_1 = initial temperature = -30^oC

Putting all the values in above equation, we get:

q_1=200g\times 0.5Cal/g^oC\times (0-(-30))^oC=3000Cal

  • <u>For process 2:</u>

q_2=m\times L_f

where,

q_1 = amount of heat absorbed = ?

m = mass of water or ice = 200 g

L_f = latent heat of fusion = 80 Cal/g

Putting all the values in above equation, we get:

q_2=200g\times 80Cal/g=16000Cal

  • <u>For process 3:</u>

q_3=m\times C_{p,l}\times (T_{2}-T_{1})

where,

q_3 = amount of heat absorbed = ?

m = mass of water = 200 g

T_2 = final temperature = 50^oC

T_1 = initial temperature = 0^oC

Putting all the values in above equation, we get:

q_3=200g\times 1Cal/g^oC\times (50-0)^oC=10000Cal

Calculating the total heat absorbed, we get:

Q=q_1+q_2+q_3

Q=3000+16000+10000=29000Cal

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7 0
3 years ago
A movie stunt driver on a motorcycle speeds horizontally off a 50.0 m high cliff. how fast must the motorcycle leave the cliff-t
Marina86 [1]
This is a projectile motion problem, so, we use the formula for trajectory:

y =xtanα + gx^2/2v^2(cosα)^2

where 
y is the vertical distance (y = 50 m)
x is the horizontal distance (x=90 m)
α is the angle of trajectory; since it levels of HORIZONTALLY, α = 0°
v is the initial velocity 
g is the acceleration due to gravity which is 9.81 m/s^2

Substituting to the formula,

50 =90tan(0°) + (9.81)(90)^2/2v^2(cos0°)^2
v = 28.2 m/s 
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Answer:

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