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3 years ago

A rock of mass m is twirled on a string in a horizontal plane. The work done by the tension in the string on the rock is:

Physics

1 answer:

Varvara68 [4.7K]3 years ago

7 0

Answer: c) 0

Explanation:

Work tension is zero because in any infinitesimal time interval, the tension force is directly perpendicular to the displacement.

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In a race, Usain Bolt accelerates at

jeka94

Answer:

65.87 s

Explanation:

For the first time,

Applying

v² = u²+2as.............. Equation 1

Where v = final velocity, u = initial velocity, a = acceleration, s = distance

From the question,

Given: u = 0 m/s (from rest), a = 1.99 m/s², s = 60 m

Substitute these values into equation 1

v² = 0²+2(1.99)(60)

v² = 238.8

v = √238.8

v = 15.45 m/s

Therefore, time taken for the first 60 m is

t = (v-u)/a............ Equation 2

t = (15.45-0)/1.99

t = 7.77 s

For the final 40 meter,

t = (v-u)/a

Given: v = 0 m/s(decelerates), u = 15.45 m/s, a = -0.266 m/s²

Substitute into the equation above

t = (0-15.45)/-0.266

t = 58.1 seconds

Hence total time taken to cover the distance

T = 7.77+58.1

T = 65.87 s

3 0

3 years ago

Carol can be defined as a social drinker because she can easily limit drinking and she chiefly drinks alcohol when she is out wi

satela [25.4K]

True. These are the characteristics of a social drinker.

6 0

4 years ago

Read 2 more answers

Approximately where is it currently high tide on Earth? Group of answer choices wherever it is currently noon anywhere that ocea

Wewaii [24]

Answer:

Option D, only on the portion of the Earth facing directly toward the Moon

Explanation:

Tides are caused by the gravitational pull of moon. The part of earth that faces the moon experiences the highest gravitational force and hence the high tides will occur in this regions only. The regions that do not faces the moon experiences low tides. It is the gravity of moon that attracts the ocean water towards itself.

Hence, Option D is correct

7 0

3 years ago

A long, current-carrying solenoid with an air core has 1800 turns per meter of length and a radius of 0.0165 m. A coil of 210 tu

Hoochie [10]

Answer:

The mutual inductance is $M = 0.000406 \ H$

Explanation:

From the question we are told that

The number of turns per unit length is $N = 1800$

The radius is $r = 0.0165 \ m$

The number of turns of the solenoid is $N_s = 210 \ turns$

Generally the mutual inductance of the system is mathematically represented as

$M = \mu_o * N * N_s * A$

Where A is the cross-sectional area of the system which is mathematically represented as

$A = \pi * r^2$

substituting values

$A = 3.142 * (0.0165)^2$

$A = 0.0008554 \ m^2$

also $\mu_o$ is the permeability of free space with the value $\mu_o = 4\pi * 10^{-7} N/A^2$

$M = 4\pi * 10^{-7} *1800 * 210 * 0.0008554$

$M = 0.000406 \ H$

3 0

3 years ago

Person is lifting a 250 N dumbbell. The weight is 30 cm from the pivot point of the elbow. What force must be exerted five from

qwelly [4]

Refer to the diagram shown below.

The force, F, is applied at 5 cm from the elbow.

For dynamic equilibrium, the sum of moments about the elbow is zero.
Take moments about the elbow.
(5 cm)*(F N) - (30 cm)*(250 N) = 0
F = (30*250)/5 = 1500 N

Answer: 1500 N

4 0

3 years ago