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zepelin [54]
3 years ago
12

You are travelling at 60.0 mph on the Grand Central Parkway near exit 10 where it is (nearly) parallel to the Long Island Expres

sway (LIE). a) A truck on the LIE going in the SAME direction as you is travelling at 55.0 mph. What is YOUR relative velocity compared to that truck? b) A truck on the LIE going in the OPPOSITE direction as you is travelling at 55.0 mph. What is YOUR relative velocity compared to that truck?
Physics
1 answer:
Romashka-Z-Leto [24]3 years ago
4 0

Answer:

a)Vr= 5 mph

b)Vr= 115 mph

Explanation:

Lets

your velocity ,u= 60 mph

velocity of truck ,v= 55 mph

When object are moving in opposite direction the relative velocity  = u +v When object are moving in opposite direction the relative velocity  = u - v

a)

Truck is moving in the same direction ,so the  relative velocity

Vr= = u - v

Vr= 60 - 55

Vr= 5 mph

b)

Truck is moving in the opposite direction ,so the  relative velocity

Vr= = u+v

Vr= 60 + 55

Vr= 115 mph

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Suppose a baseball pitcher throws the ball to his catcher.
amm1812

a) Same

b) Same

c) Same

d) Throw the ball takes longer

e) F is larger when the ball is catched

Explanation:

a)

The change in speed of an object is given by:

\Delta v = |v-u|

where

u is the initial velocity of the object

v is the final velocity of the object

The change in speed is basically the magnitude of the change in velocity (because velocity is a vector, while speed is a scalar, so it has no direction).

In this problem:

- In situation 1 (pitcher throwing the ball), the initial velocity is

u = 0 (because the ball starts from rest)

while the final velocity is v, so the change in speed is

\Delta v=|v-0|=|v|

- In situation 2 (catcher receiving the ball), the initial velocity is now

u = v

while the final velocity is now zero (ball coming to rest), so the change in speed is

\Delta v =|0-v|=|-v|

Which means that the two situations have same change in speed.

b)

The change in momentum of an object is given by

\Delta p = m \Delta v

where

m is the mass of the object

\Delta v is the change in velocity

If we want to compare only the magnitude of the change in momentum of the object, then it is given by

|\Delta p|=m|\Delta v|

- In situation 1 (pitcher throwing the ball), the change in momentum is

\Delta p = m|\Delta v|=m|v|=mv

- In situation 2 (catcher receiving the ball), the change in momentum is

\Delta p = m\Delta v = m|-v|=mv

So, the magnitude of the change in momentum is the same (but the direction is opposite)

c)

The impulse exerted on an object is equal to the change in momentum of the object:

I=\Delta p

where

I is the impulse

\Delta p is the change in momentum

As we saw in part b), the change in momentum of the ball in the two situations is the same, therefore the impulse exerted on the ball will also be the same, in magnitude.

However, the direction will be opposite, as the change in momentum has opposite direction in the two situations.

d)

To compare the time of impact in the two situations, we have to look closer into them.

- When the ball is thrown, the hand "moves together" with the ball, from back to ahead in order to give it the necessary push. We can verify therefore that the time is longer in this case.

- When the ball is cacthed, the hand remains more or less "at rest", it  doesn't move much, so the collision lasts much less than the previous situation.

Therefore, we can say that the time of impact is longer when the ball is thrown, compared to when it is catched.

e)

The impulse exerted on an object can also be rewritten as the product between the force applied on the object and the time of impact:

I=F\Delta t

where

I is the impulse

F is the force applied

\Delta t is the time of impact

This can be rewritten as

F=\frac{I}{\Delta t}

In this problem, in the two situations,

- I (the impulse) is the same in both situations

- \Delta t when the ball is thrown is larger than when it is catched

Therefore, since F is inversely proportional to \Delta t, this means that the force is larger when the ball is catched.

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Answer:

yes

Explanation:

this is simple

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Atom A and atom C are the same element.

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