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2 years ago

When an object slides,there is less friction than when it rolls

Physics

1 answer:

Butoxors [25]2 years ago

4 0

Answer:

False

Explanation:

Rolling friction takes place when an object rolls on the surface. Sliding friction takes place when two surfaces are rubbed against each other. Rolling friction is much less than sliding friction for same pair of bodies. When one body rolls upon another, there is theoretically no sliding or slip between them.

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Two students are on a balcony 19.1 m above the street. One student throws a ball, b1, vertically downward at 13.9 m/s. At the sa

tester [92]

Answer:

Part a)

$t = 2.83 s$

Part b)

Ball thrown downwards = $v_f = 23.8 m/s$

Ball thrown upwards = $v_f = 23.8 m/s$

Part c)

$d = 22.24 m$

Explanation:

Part a)

Since both the balls are projected with same speed in opposite directions

So here the time difference is the time for which the ball projected upward will move up and come back at the same point of projection

Afterwards the motion will be same as the first ball which is projected downwards

so here the time difference is given as

$\Delta y = 0 = v_y t + \frac{1}{2}at^2$

$0 = 13.9 t - \frac{1}{2}(9.81) t^2$

$t = 2.83 s$

Part b)

Since the displacement in y direction for two balls is same as well as the the initial speed is also same so final speed is also same for both the balls

so it is given as

$v_f^2 - v_i^2 = 2 a \Delta y$

$v_f^2 - (13.9)^2 = (2)(-9.81)(-19.1)$

$v_f^2 = 567.9$

$v_f = 23.8 m/s$

Part c)

Relative speed of two balls is given as

$v_{12} = v_1 - v_2$

$v_{12} = (13.9) - (-13.9) = 27.8 m/s$

now the distance between two balls in 0.8 s is given as

$d = v_{12} t$

$d = 27.8 \times 0.8$

$d = 22.24 m$

7 0

3 years ago

In which material does the light wave have the larger wavelength?

pochemuha

Answer: in the smaller/ thinner pieces.

8 0

2 years ago

Students will consider the following items: ice, glass, copper, and aluminium. what happens to each item when hammered? what pro

vladimir2022 [97]

All metals except potassium and sodium, have a property known as malleability. Malleability is the quality of something that can be shaped into something else without breaking. So when aluminium and copper are hammered they will not break. Rather they will change shape and become thin or flat at the area where its hammered.

All Non- metals except diamond are brittle in nature, so when we hammer it , they will break down into pieces. So when ice and glass will be hammered they will shatter into pieces.

4 0

3 years ago

Which of the following choices concerning the net magnetic flux through any enclosed surface is true according to Gauss' law for

11Alexandr11 [23.1K]

Answer:

e. The net magnetic flux in this case would be equal to zero.

Explanation:

As per Gauss law of magnetism we need to find the net magnetic flux through a closed loop

here we know that net magnetic flux is the scalar product of magnetic field vector and area vector

so here we have

$\int B. dA$ = net magnetic flux

since we know that magnetic field always forms closed loop so if we find the integral over a closed loop

then in that case the value of the close integral must be zero

so correct answer would be

e. The net magnetic flux in this case would be equal to zero.

6 0

3 years ago

An empty truck traveling at 10 km/h has kinetic energy. How much kinetic energy does it have when loaded so that its mass and it

Katena32 [7]

Answer:

8 time increase in K.E.

Explanation:

Consider Mass of truck = m kg and speed = v m/s then

K.E. = 1/2 ×mv²

If mass and speed both are doubled i.e let m₀ = 2m and v₀ = 2v then

(K.E.)₀ = 1/2 ×2m(2v)²

(K.E.)₀ = 8 (1/2 × mv²) = 8 × K.E.

7 0

3 years ago