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4 years ago

A car accelerates uniformly in a straight line

Physics

1 answer:

kotegsom [21]4 years ago

6 0

The car covers a distance d after time t of

d = (2.8 m/s²) t²

Solve for t when d = 69 m:

69 m = (2.8 m/s²) t²

t² = (69 m) / (2.8 m/s²)

t ≈ 4.96 s

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Consider the three dip1acement vectors A = (3i - 3j) m, B = (i-4j) m, and C = (-2i + 5j) m. Use the component method to determin

tia_tia [17]

Answer with Explanation:

We are given that

A=3i-3j m

B=i-4 j m

C=-2i+5j m

a. $D=A+B+C$

$D=3i-3j+i-4j-2i+5j$

$D=2i-2j$

Compare with the vector r=xi+yj

We get x=2 and y=-2

Magnitude= $\mid D\mid=\sqrt{x^2+y^2}=\sqrt{(2)^2+(-2)^2}=2\sqrt 2$ units

By using the formula $\mid r\mid=\sqrt{x^2+y^2}$

Direction: $\theta=tan^{-1}\frac{y}{x}$

By using the formula

Direction of D: $\theta=tan^{-1}(\frac{-2}{2})=tan^{-1}(-1)=tan^{-1}(-tan45^{\circ})=-45^{\circ}$

b.E=-A-B+C

$E=-3i+3j-i+4j-2i+5j$

$E=-6i+12j$

$\mid E\mid=\sqrt{(-6)^2+(12)^2}=13.4$ units

Direction of E= $\theta=tan^{-1}(\frac{12}{-6}=tan^{-1}(-2)=-63.4^{\circ}$

4 0

4 years ago

The fall of a body on the earth's surface cannot be a complete free fall why ?

leonid [27]

Explanation:

because the boy has larger surface area due to which he offers the larger air resistance which decreases the acceleration so, he will fall towards the earth's surface approximately with constant velocity.

3 0

3 years ago

How can you use Newton's second law to find force

Citrus2011 [14]

Newton's second law is F = ma where F is force, m is mass, and a is acceleration. If you know the mass and acceleration of an object you can find it's force using his formula.

3 0

3 years ago

In a "worst-case" design scenario, a 2000 kg elevator with broken cables is falling at 4.00 m/s when it first contacts a cushion

Leno4ka [110]

Answer:

4 m/s²

Explanation:

When the elevator is 1 m below point of contact , compression will be 1 m.

Restoring force in the spring will be 10600 N. Friction force of 17000N will also act in upward direction . The weight of 2000 x 9.8 N will act downwards

Force in down ward direction = 2000 x 9.8

= 19600 N

Force in upward direction

= 10600 + 17000

= 27600 N

Net force in upward direction

= 27600 - 19600

= 8000 N

Acceleration in upward direction

= 8000 / 2000

= 4 m/s²

5 0

4 years ago

Dancing has been part of almost every human civilization. A. True B. False

lesantik [10]

True because almost every civilization we see on the past had a form of dance to express themselves.

8 0

4 years ago