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3 years ago

Objects in free fall are weightless.

Physics

1 answer:

Murljashka [212]3 years ago

4 0

Answer:

$\boxed{True}$

Explanation:

Objects are weightless in free fall because their is no other force pushing them rather than the gravitational force.

Hope it helps!<3

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A 55 kg cheerleader uses an oil-filled hydraulic lift to hold four 110 kg football players at a height of 1.0 m. If her piston i

AVprozaik [17]

Answer:

$D = 55.2 cm$

Explanation:

As we know that the total mass of the all four players is given as

$M = 4\times 110$

$M = 440 kg$

diameter of the piston of cheer leader is given as

$d_1 = 16 cm$

are of cross-section is given as

$A_1 = \pi r^2$

$A_1 = \pi(0.08)^2 = 0.02 m^2$

mass of the cheer leader is given as

m = 55 kg

so the pressure due to cheer leader is given as

$P_{in} = \frac{mg}{A_1}$

$P_{in} = \frac{55 \times 9.81}{0.02}$

$P_{in} = 26835 Pa$

Now on the other side pressure must be same

so we have

$\frac{Mg}{A} + \rho gH = P_{in}$

$\frac{440 \times 9.8}{A} + (900)(9.8)(1) = 26835$

$A = 0.24 m^2$

$\pi r^2 = 0.24$

$r = 0.276 m$

so diameter on the other side is given as

$D = 2 r$

$D = 55.2 cm$

8 0

3 years ago

An unwary football player collides with a padded goalpost while running at a velocity of 7.50 m/s and comes to a full stop after

mr Goodwill [35]

Answer:

(a) 80.36 m/s^2

(b) 0.0933 second

Explanation:

initial velocity, u = 7.5 m/s

final velocity, v = 0 m/s

distance moved, s = 0.350 m

(a) Let a be the deceleration.

Use third equation of motion

$v^{2}=u^{2}+2\times a\times s$

$0^{2}=7.5^{2}+2\times a\times 0.350$

a = 80.36 m/s^2

Thus, the deceleration is 80.36 m/s^2.

(b) Let the time taken is t

Use first equation of motion

v = u + a t

0 = 7.5 + 80.36 x t

t = 0.0933 second

7 0

3 years ago

a 905 - g meteor impacts the earth at a speed of 1623 m/s. if all of its energy is entirely converted to heat in the meteor, wha

nlexa [21]

Answer: 2859.78 k

Explanation: By using the law of conservation of energy, the kinetic energy of the meteor equals the heat energy.

Kinetic energy = 1/2mv^2

Heat energy = mcΔθ

Where m = mass of meteor , v = velocity of meteor = 1623 m/s

c = specific heat capacity of meteor (iron) = 460.548 j/kg/k

Δθ = change in temperature of meteor = ?

From law ofconservation of energy, we have that

1/2mv^2 = mcΔθ

By cancelling "m" on both sides, we have that

v^2/2 = cΔθ

v^2 = 2cΔθ

(1623)^2 = 2× 460.548 × Δθ

2634129 = 921.096 × Δθ

Δθ = 2634129 / 921.096

Δθ = 2859.78 k

6 0

3 years ago

A 20-ton truck collides with a 1500-lb car and causes a lot of damage to the car. During the collision:

dexar [7]

Answer:

B. the force of on the truck due to the collision is exactly equal to the force on the car.

Explanation:

At the time of collision between two objects of unequal or equal masses two forces emerge at the point of collision .They are called action and reaction force . According to third law of Newton , they are equal . So in the instant case of collision between car and truck , force on both of them will be equal.

6 0

3 years ago

Can someone tell me the answer and the reason

spin [16.1K]

Answer:

(a) the blocks all had different masses.

Explanation:

The surface is smooth, therefore coefficient of friction is tending to zero.

Forces for each blocks varied from 6N to 8N to 7N to 5N

The blocks were made of different materials and different materials are going to have varying weight for the same size of block.

8 0

4 years ago