Answer:
4Q
Explanation:
Case 1 :
= mass of the metal
= specific heat of the metal
= Change in temperature = 7 - 4 = 3 C
Amount of heat required for the above change of temperature is given as

Case 2 :
= mass of the metal
= specific heat of the metal
= Change in temperature = 19 - 7 = 12 C
Amount of heat required for the above change of temperature is given as

Hence the correct choice is
4Q
Answer:
F = 263.51 N
Explanation:
given,
diameter of wheel = 78 cm
diameter of axle = 14.8 cm
Force exerted on the rim of wheel = 150 N
Force applied outside the axle = ?
To prevent rotation wheel from rotating the Force 'F' should be applied outside of the axle.
Net momentum about the center of mass should be zero
now,
Moment of about center due to 150 N = moment about center due to F on axle

7.4 F = 1950
F = 263.51 N
Hence, Force exerted outside of the axle in order to prevent the wheel from rotating is equal to 263.51 N.
You will need to turn this into scientific notation, so:
1.176 × 10^1 cm^2
To two significant figures means to two digits so since 7 is greater than 5, you will need to round up.
Final answer is:
1.2×10^1 cm^2