Ask question

Ask question

All categories

3 years ago

7

Two cars are raised to the same elevation on service- station lifts. If one car is twice as massive as the other, how do their p

otential energies compare?

1 answer:

Brums [2.3K]3 years ago

7 0

Answer:

The potential energy of the more massive one is twice that of the other.

Explanation:

Potential energy is given by

<em>PE</em> = <em>mgh</em>

where <em>m</em> = mass of body, <em>g</em> = acceleration of gravity and <em>h</em> = height or elevation.

For the less massive car, let the mass be $m_1$ . Then its <em>PE</em> is

$PE_1 = m_1gh$

For the massive car, let the mass be $m_2$ . Its <em>PE</em> is

$PE_2 = m_2gh$

But $m_2 =2m_1$

$\therefore PE_2 = 2m_1gh = 2(m_1gh) = 2PE_1$

Hence, the potential energy of the more massive one is twice that of the other.

You might be interested in

A person is lying on a diving board 3.50 m above the surface of the water in a swimming pool. She looks at a penny that is on th

sergij07 [2.7K]

Answer:

1.995 m

Explanation:

Distance of penny as seen by the person = 5 m

Height of person from water surface = 3.50 m

Apparent depth of penny = 5 - 3.50 = 1.5 m

refractive index of water, n = 1.33

real depth / apparent depth = n

real depth = 1.33 x 1.5 = 1.995 m

Thus, the actual depth of water at that point is 1.995 m.

4 0

3 years ago

Block B is attached to a massless string of length L = 1 m and is free to rotate as a pendulum. The speed of block A after the c

Amanda [17]

Complete Question

The diagram for this question is shown on the first uploaded image

Answer:

The minimum velocity of A is $v_A= 4m/s$

Explanation:

From the question we are told that

The length of the string is $L = 1m$

The initial speed of block A is $u_A$

The final speed of block A is $v_A = \frac{1}{2}u_A$

The initial speed of block B is $u_B = 0$

The mass of block A is $m_A = 7kg$ gh

The mass of block B is $m_B = 2 kg$

According to the principle of conservation of momentum

$m_A u_A + m_B u_B = m_Bv_B + m_A \frac{u_A}{2}$

Since block B at initial is at rest

$m_A u_A = m_Bv_B + m_A \frac{u_A}{2}$

$m_A u_A - m_A \frac{u_A}{2} = m_Bv_B$

$m_A \frac{u_A}{2} = m_Bv_B$

making $v_B$ the subject of the formula

$v_B =m_A \frac{u_A}{2 m_B}$

Substituting values

$v_B =\frac{7 u_A}{4}$

This $v__B$ is the velocity at bottom of the vertical circle just at the collision with mass A

Assuming that block B is swing through the vertical circle(shown on the second uploaded image ) with an angular velocity of $v__B'$ at the top of the vertical circle

The angular centripetal acceleration would be mathematically represented

$a= \frac{v^2_{B}'}{L}$

Note that this acceleration would be toward the center of the circle

Now the forces acting at the top of the circle can be represented mathematically as

$T + mg = m \frac{v^2_{B}'}{L}$

Where T is the tension on the string

According to the law of energy conservation

The energy at bottom of the vertical circle = The energy at the top of

the vertical circle

This can be mathematically represented as

$\frac{1}{2} m(v_B)^2 = \frac{1}{2} mv^2_B' + mg 2L$

From above

$(T + mg) L = m v^2_{B}'$

Substitute this into above equation

$\frac{1}{2} m(\frac{7 v_A}{4} )^2 = \frac{1}{2} (T + mg) L + mg 2L$

$\frac{49 mv_A^2}{16} = \frac{1}{2} (T + mg) L + mg 2L$

$\frac{49 mv_A^2}{16} = T + 5mgL$

The value of velocity of block A needed to cause B be to swing through a complete vertical circle is would be minimum when tension on the string due to the weight of B is zero

This is mathematically represented as

$\frac{49 mv_A^2}{16} = 5mgL$

making $v_A$ the subject

$v_A = \sqrt{\frac{80mgL}{49m} }$

substituting values

$v_A = \sqrt{\frac{80* 9.8 *1}{49} }$

$v_A= 4m/s$

6 0

3 years ago

A pie is cooked in an oven at 200 °C. The aluminium film that ckvered the pie can be touched soon after it is removed while the

GREYUIT [131]

Answer and Explanation:

The aluminum is more productive in the absorption and heat transfer to other particles. It instantly converts heat absorbed from the environment into the atmosphere when removed from the oven, enabling us to operate with it faster than the pie that takes much longer to convert heat to the environment.

So this is the reason for pie to be the dangerously hot

8 0

3 years ago

musickatia [10]

Answer:

C

Explanation:

4 0

3 years ago

A student is trying to calculate the density of an ice cream cone. She already knows the mass, but she needs to determine the vo

vladimir2022 [97]

V= 1/3 π r²h
this is the formula for a cone hope this helps :)

5 0

3 years ago

Read 2 more answers