Physics, 19.02.2020 05:27 eylinglez3ovm16v

A car moving at 8 m/s crashes into a barrier and stops in 0.050 s. There is a 19-kg child in the car. Assume that the child's velocity is changed by the same amount as that of the car, and in the same time period. (a) What is the impulse needed to stop the child in N*s?(b) What is the average force on the child in N? (c) What is the approximate mass of an object in kg whose weight equals the force in part (b)?

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Answer from: Amyra2003

(a).The impulse needed to stop the child is 152 kg m/s.

(b). The average force on the child is 3040 N.

(c). The approximate mass of an object is 310.2 kg

Explanation:

Given that,

Speed of car = 8 m/s

Mass of child = 19 kg

Time = 0.050 s

(a). We need to calculate the impulse needed to stop the child

Using formula of impulse

$J=m\Delta v$

$J=m\times (v_{f}-v_{i})$

$J=19\times(0-8)$

$J=-152\ kgm/s$

Negative sign shows the net force is in negative direction.

The impulse needed to stop the child is 152 kg m/s.

(b). We need to calculate the average force on the child

Using formula of impulse

J=Ft

$F=\dfrac{J}{t}$

Put the value into the formula

$F=\dfrac{-152}{0.05}$

$F=−3040\ N$

Negative sign shows the opposite direction of the force

The average force on the child is 3040 N.

(c). We need to calculate the approximate mass of an object

Using formula of force

F=mg

$m=\dfrac{F}{g}$

Put the value into the formula

$m=\dfrac{3040}{9.8}$

$m=310.2\ kg$

The approximate mass of an object is 310.2 kg

Hence, (a).The impulse needed to stop the child is 152 kg m/s.

(b). The average force on the child is 3040 N.

(c). The approximate mass of an object is 310.2 kg

Answer from: Quest

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm. the wire diameter is d = 0.9 mm. the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2) in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation:

Answer from: Quest

what was the acceleration of the 2 kg cart?

⇒ 16.0 cm/s2

what was the acceleration of the 4 kg cart?

⇒ 8.1 cm/s2

what was the acceleration of the 6 kg cart?

⇒ 5.3 cm/s2

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A car moving at 8 m/s crashes into a barrier and stops in 0.050 s. There is a 19-kg child in the car...