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Amanda [17]
3 years ago
12

A railroad car moves under a grain elevator at a constant speed of 3.20 m/s. Grain drops into the car at the rate of 240 kg/min.

What is the magnitude of the force needed to keep the car moving constant speed if friction is negligible?
Physics
1 answer:
dedylja [7]3 years ago
5 0

Answer:

F = 768 N                  

Explanation:

It is given that,

Speed of the elevator, v = 3.2 m/s

Grain drops into the car at the rate of 240 kg/min, \dfrac{dm}{dt}=240\ kg/min = 4\ kg/s

We need to find the magnitude of force needed to keep the car moving constant speed. The relation between the momentum and the force is given by :

F=\dfrac{dp}{dt}

F=m\dfrac{dv}{dt}+v\dfrac{dm}{dt}

Since, the speed is constant,

F=m\dfrac{dv}{dt}

F=v\dfrac{dm}{dt}

F=3.2\times 240

F = 768 N

So, the magnitude of force need to keep the car is 768 N. Hence, this is the required solution.

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What force does a trampoline have to apply to a 45.0-kg gymnast to accelerate her straight up at 7.50 m/s^2? (a) 104N (b) 338 N
Brilliant_brown [7]

Answer:

b) 338 N

Explanation: let m be the mass of the gymnast and a be the acceleration of the gymnast.

the force required to accelerate the gymnast is given by:

F = m×a

  = (45.0)×(7.50)

  = 337.5 N

Therefore, the force a trampoline has to apply is 138 N.

6 0
3 years ago
A projectile is fired horizontally from a height of 78.4 m at a speed of 300 m/sec. How far did it travel horizontally before hi
Mice21 [21]

Answer:

Explanation:

Using the formula for calculating range expressed as;

R = U√2H/g

U is the speed = 300m/s

H is the maximum height = 78.4m

g is the acceleration due to gravity = 9.8m/s²

Substitute into the fromula;

R = 300√2(78.4)/9.8

R = 300 √(16)

R = 300*4

R = 1200m

Hence the projectile travelled 1200m before hitting the ground

3 0
3 years ago
The typical unit for a period used with Kepler's third law is
ollegr [7]
Well, if you're using the law to work with periods of Earth satellites,
then the most convenient unit is going to be 'hours' for the largest
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But if you're using it to work with periods of planets, asteroids, or
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6 0
3 years ago
A 20 kg bike accelerates at 10 m/s2. What was the force?
agasfer [191]

Answer:

200 N = 200 Newtons

Explanation:

Just use the formula F = m*a

F = Force in Newtons

m = mass and is 20 kg

a = acceleration and is 10 m/s^2

F = 20 * 10

F = 200 Newtons.

7 0
3 years ago
a swimmer experiences a total (absolute) pressure of 117,500 pa in a pool. how far below the surface are they located?
marta [7]

Answer:

Explanation:

We know that the pressure can be calculated in the following way:

p = d·g·h

with d being the density of the water, g the gravitational acceleration and h the depth.

Also d of the water = 1000 kg/m^3 circa and g = 9.8 m/s^2 circa

117,500 Pa = 1000kg/m³ · 9.8m/s² · h

Therefore h = 11,9 m

4 0
2 years ago
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