Calculate the average speed of a runner who runs for 500 meters in 40 second HELP!

What impulse occurs when an average force of 7.0 N is exerted on a cart for 2.5 s ?

makkiz [27]

Answer: $1.7\times 10$

Explanation:

Given

Force $F=7 N$

time interval $t=2.5 s$

Impulse is given by $=Force \times time\ interval\ for\ applied\ force$

$Impulse=7\times 2.5=17.5$

For two significant Figure

$Impulse=1.7\times 10$

7 0

3 years ago

A 17-car train standing on the siding is started in motion by the train’s engine. 9 cm slack is between each of the cars, which

BaLLatris [955]

Answer:

4 seconds

Explanation:

There are links between cars, they are in between

1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-16, 16-17.

Here 1 represents the first car which is firmly attached to the engine. So, there are 16 links and each link has a slack of 9 m.

So, total slack

9×16 = 144 cm

Speed of train = 36 cm/s

$\text{Time taken by the pulse}=\frac{Length}{speed}\\\Rightarrow \text{Time taken by the pulse}=\frac{144}{36}\\\Rightarrow \text{Time taken by the pulse}=4\ s$

Time taken by the pulse to travel the length of train is 4 seconds.

6 0

3 years ago

What is the transfer of energy by electromagnetic waves

Ann [662]

The transfer of energy by electromagnetic waves is called electromagnetic radiation

3 0

4 years ago

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A box is being moved with a velocity (v) by a force P (parallel to v) along a level horizontal floor. The normal force is (Fn),

labwork [276]

Answer:

Force (P) : Positive

Normal Force (Fn) : Zero

Weight (mg) : Zero

Kinetic Frictional Force (fk) : Negative

Explanation:

The work done by a force on an object is given by the following formula:

W = F.d

W = F d Cosθ

where,

W = Work Done

f = Force Applied

d = displacement

θ = Angle between force and displacement

FOR FORCE (P):

Since, force P is parallel to the motion of the box. Therefore, θ = 0°

Hence,

W = P d Cos 0°

W = P d(1)

W = Pd

Therefore, work done by force (P) is Positive.

FOR NORMAL FORCE (Fn) AND WEIGHT (W):

Since, normal force and weight are perpendicular to the motion of the box. Therefore, θ = 90°

Hence,

W = Fn d Cos 90°= mg d Cos 90°

W = Fn d(0) = mg d (0)

W = 0

Therefore, work done by Normal Force (Fn) and Weight (mg) is Zero.

FOR KINETIC FRICTIONAL FORCE (fk):

Since, kinetic frictional force acts in the opposite direction of motion of the box. Therefore, θ = 180°

Hence,

W = fk d Cos 180°

W = fk d(-1)

W = -fk d

Therefore, work done by Kinetic Frictional Force (fk) is Negative.

8 0

4 years ago

Why does salt dissolve in water act as an antifreeze?

aalyn [17]

Answer:

A

Explanation:

An antifreeze is a substance which when added to a liquid reduces the freezing point of the liquid. Hence the solution can only freeze at a lower temperature compared to the solvent. Examples of antifreeze includes salt and propylene glycol. Antifreeze are used in low temperature environments to prevent water from freezing quicky. Hence the answer is A.

Have a great day Aylabailey4930

8 0

3 years ago

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