Pls help me I want to get this done

rodikova [14]

1. B
2.D
3.C
4.B

Hope this helped. Good luck!

3 0

3 years ago

An arrow of 43 g moving at 84 m/s to the right, strikes an apple at rest. The arrow sticks to the apple and both travel at 16.8

Aloiza [94]

Answer:

<em>The mass of the apple is 0.172 kg (172 g)</em>

Explanation:

<u>The Law Of Conservation Of Linear Momentum </u>

The total momentum of a system of bodies is conserved unless an external force is applied to it. The formula for the momentum of a body with mass m and speed v is

P=mv.

If we have a system of two bodies, then the total momentum is the sum of both momentums:

$P=m_1v_1+m_2v_2$

If a collision occurs and the velocities change to v', the final momentum is:

$P'=m_1v'_1+m_2v'_2$

Since the total momentum is conserved, then:

P = P'

Or, equivalently:

$m_1v_1+m_2v_2=m_1v'_1+m_2v'_2$

If both masses stick together after the collision at a common speed v', then:

$m_1v_1+m_2v_2=(m_1+m_2)v'$

We are given the mass of an arrow m1=43 g = 0.043 kg traveling at v1=84 m/s to the right (positive direction). It strikes an apple of unknown mass m2 originally at rest (v2=0). The common speed after they collide is v'=16.8 m/s.

We need to solve the last equation for m2:

$m_2v_2-m_2v'=m_1v'-m_1v_1$

Factoring m2 and m1:

$m_2(v_2-v')=m_1(v'-v_1)$

Solving:

$\displaystyle m_2=\frac{m_1(v'-v_1)}{v_2-v'}$

Substituting:

$\displaystyle m_2=\frac{0.043(16.8-84)}{0-16.8}$

$\displaystyle m_2=\frac{-2.8896}{-16.8}$

$\displaystyle m_2=0.172\ kg$

The mass of the apple is 0.172 kg (172 g)

3 0

3 years ago

A metal bar, pivoted at one end, oscillates freely in the absence of a magnetic field. But when it oscillates between the poles

miv72 [106K]

Explanation:

When the metal bar oscillates between the poles of a magnet, it experience a change in the magnetic flux ( no of magnetic field lines passing through the metal bar) as it enter or leaves the magnetic field of the poles. As we know that the change in magnetic field induces the electric current in the metal bar (conductor). By considering the lenz law which states that the direction of induced current in the conductor will be such that as to oppose the initial magnetic field that is producing it. This opposing force acting on the metal bar will damp the oscillations of the bar between the poles of a magnet.

8 0

3 years ago

A car of mass 1800 kg can be just be lifted. What is the least force that the electromagnet must use to lift the car? (1 g = 10

Doss [256]

Answer:

m=1800kg

1800000g×10N/kg

18000000N force is required to life the car

8 0

3 years ago

When and why was the metric system invented?

inna [77]

The first practical realisation of the metric system came in 1799, during the French Revolution, when the existing system of measures, which had become impractical for trade, was replaced by a decimal system based on the kilogram and the metre.

3 0

3 years ago