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lisabon 2012 [21]
4 years ago
8

4. A student throws a set of keys vertically upward to her sorority sister, who is in a window 4.00 m above. The second student

catches the keys 1.50 s later. (a) With what initial velocity were the keys thrown? (b) What was the velocity of the keys just before they were caught?​
Physics
1 answer:
lorasvet [3.4K]4 years ago
3 0

Answer:

a) 10.0 m/s

b) -4.68 m/s

Explanation:

Given:

y₀ = 0 m

y = 4.00 m

t = 1.50 s

a = -9.8 m/s²

Find: v₀, v

y = y₀ + v₀ t + ½ at²

4.00 = 0 + v₀ (1.50) + ½ (-9.8) (1.50)²

v₀ = 10.0 m/s

v = at + v₀

v = (-9.8) (1.50) + 10.0

v = -4.68 m/s

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About how long does it take the sun to rotate once about its axis?
Troyanec [42]

Very very roughly, an Earth month.

The Sun isn't solid, so it doesn't all have to rotate at the same rate. Different latitudes actually rotate at different speeds. One complete rotation is about 24 days at the Sun's equator, but 35 days near the poles !

6 0
3 years ago
A car travels on the entrance ramp to a freeway as it accelerates from 30 mph to the freeway speed of 70 mph for 4.0 s. Suppose
vova2212 [387]

Answer:

a) distance d = 293.36ft

b) acceleration a = 14.67ft/s^2

Explanation:

Acceleration is the change in velocity per unit time.

a = ∆v/t ....1

Given;

Initial velocity vi = 30mph × 5280ft/mile × 1/3600s/h

vi = 44ft/s

Final velocity vf = 70mph × 5280ft/mile × 1/3600s/h

vf = 102.67ft/s

time = 4.0s

From equation 1, acceleration is;

a = ∆v/t = (102.67-44)/4 = 14.67ft/s^2

Distance travelled can be given as;

d = ut + 0.5at^2 .....2

u = 44ft/s

t = 4

a = 14.67ft/s^2

Substituting into the equation 2

d = 44(4) + 0.5(14.67×4^2)

d = 293.36ft

5 0
3 years ago
What is the kinetic energy of a 0.50 kg ball traveling at 120 m/s
MatroZZZ [7]

Answer:

3600 J

Explanation:

Kinetic energy of an object is the energy posses by an object solely due to its motion.

It can also be defined as the amount of work that can be done when an moving object come to test.

Kinetic energy of an object can be calculated by the equation,

K.E. = ½mv²

Where m = mass, v = velocity

So you get,

K.E. = ½×0.5×(120)² = 3600 J

8 0
3 years ago
A car bounces up and down on its springs at 1.0 Hz with only the driver in the car. Now the driver is joined by four friends. Th
romanna [79]

The new frequency of oscillation when the car bounces on its springs is 0.447 Hz

<h3>Frequency of oscillation of spring</h3>

The frequency of oscillation of the spring is given by f = (1/2π)√(k/m) where

  • k = spring constant and
  • m = mass on spring

Now since k is constant, and f ∝ 1/√m.

So, we have f₂/f₁ = √(m₁/m₂) where

  • f₁ = initial frequency of spring = 1.0 Hz,
  • m₁ = mass of driver,
  • f₂ = final frequency of spring and
  • m₂ = mass on spring when driver is joined by 4 friends = 5m₁

So, making f₂ subject of the formula, we have

f₂ = [√(m₁/m₂)]f₁

Substituting the values of the variables into the equation, we have

f₂ = [√(m₁/m₂)]f₁

f₂ = [√(m₁/5m₁)]1.0 Hz

f₂ = [√(1/5)]1.0 Hz

f₂ = 1.0 Hz/√5

f₂ = 1.0 Hz/2.236

f₂ = 0.447 Hz

So, the new frequency of oscillation when the car bounces on its springs is 0.447 Hz

Learn more about frequency of oscillation of spring here:

brainly.com/question/15318845

7 0
2 years ago
The the figure shows a famous roller coaster ride. You can ignore friction. If the roller coaster leaves Point Q from rest, what
ch4aika [34]

Answer:

22 m/s

Explanation:

PEf +KEf =PE0 +KE0 →PE0 −PEf =KEf

−mgΔy= 1 mv2 →v= −2gΔy = −2(9.8 m/s2)(−25 m)=22 m/s

3 0
3 years ago
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