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mart [117]
2 years ago
8

An ice skater slides in a straight line across the ice. As she passes a certain point, her velocity is 24 km/hr. Two seconds lat

er it is 13 km/hr. What is the acceleration of the skater?
5.5 km/hr/sec
-5.5 km/hr/sec
11 km/hr/sec
-11 km/hr/sec
Physics
1 answer:
gulaghasi [49]2 years ago
5 0
Acceleration = (change in speed) / (time for the change)

Change in speed = (later speed) - (earlier speed) = (13 - 24) = -11 km/hr
Time for the change = 2 seconds

Acceleration = (-11 km/hr) / (2 sec)

Acceleration = -5.5 km/hr-sec  (B)
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A 2.5 g bullet traveling at 350 m/s hits a tree and slows uniformly to a stop while penetrating a distance of 12 cm into the tre
Cloud [144]

Answer: Work done = 153.125Joules, Work done = 0.003Nm

Explanation:

Kinetic energy of a body is the energy possessed by a body by virtue of its motion.

Mathematically,

K.E = 1/2MV²

Where;

M = mass of the body = 2.5g = 0.0025kg

V = velocity of the body = 350m/s

Substituting this values in the formula, we have;

K.E = 1/2× 0.0025×350²

K.E = 153.125Joules

Work done is the force applied to body to cause it to move through a distance.

Work = Force × distance

Force = ma = 0.0025 × 10

Force = 0.025N

Distance = 12cm = 0.12m

Work = 0.025×0.12

Work = 0.003Nm

work done by the tree in stopping the bullet is 0.003N

4 0
3 years ago
Read 2 more answers
A proton is released in a uniform electric field, and it experiences an electric force of 2.04×10−14 N toward the south.
Lemur [1.5K]

Answer:

Part A:

E=127500N/C\\E=1.275*10^{5} N/C

Part B:

Option B (Towards the South)

Explanation:

Part A:

Magnitude if electric field E:

E=Force/charge

Force=2.04×10−14 N

Charge=1.6×10−19 C

E=\frac{2.04*10^{-14}}{1.6*10^{-19}} \\E=127500N/C\\E=1.275*10^{5} N/C

Part B:

Option B (Towards the South)

As electron is experiencing the force towards south,it means the direction of the electric field is towards the south because direction of field lines is from positive to negative, so proton is moving towards south it means negative charge is in south to which proton is attracted. So electric field is towards South.

7 0
3 years ago
Type the correct answer in each box. Use numerals instead of words.
ser-zykov [4K]

Answer:

6.23 newtons per second?

Explanation:

4 0
2 years ago
Most street lights are made from one or two elements mercury or sodium. Explain why astronomers preferred that cities you sodium
lora16 [44]
Mercury is very harmful to the average human being. the mercury can easily be released from the lamp if the lamp is knocked over and broken. mercury is also harmful if inhaled. sodium on the other hand is not harmful in any way.
4 0
3 years ago
Use the graph below to answer the following question: if average acceleration is calculated using the equation, “ change in velo
sergiy2304 [10]

Answer:

a=9\ cm/s^2

Explanation:

<u>Average Acceleration </u>

Acceleration is a physical magnitude defined as the change of velocity over time. When we have experimental data, we can compute it by calculating the slope of the line in velocity vs time graph.

Note: <em>We cannot see if the time axis is numbered in increments of 1 second, and we'll assume that. </em>

When t_2=4\ sec, the graph shows a value of v_2=36\ cm/s

When t_1=0\ sec, the object is at rest, v_1=0

We compute the average acceleration as

\displaystyle a=\frac{v_2-v_1}{t_2-t_1}

\displaystyle a=\frac{36\ cm/s-0\ cm/s}{4\ sec-0\ sec}

\displaystyle a=\frac{36\ cm/s}{4\ s}

\boxed{a=9\ cm/s^2}

6 0
2 years ago
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