Question

47 a system with no outside force is called:
a. phenomenon
b. collision
c. closed
d. theory

48 two cars collide and stick together. their momentum is:
a. added together
b. lost
c. reduced to zero
d. increased

49 which factor does not affect momentum?
a. mass
b. speed
c. temperature
d. direction (only the sign changes)

50 if mass stays the same but speed doubles, momentum will:
a. stay the same
b. double
c. triple
d. drop to zero

Answer:

To solve these physics - related multiple - choice questions, we analyze each one based on the concepts of momentum and related physics principles:

Question 48

• Concept: In a collision where two objects collide and stick together (a perfectly inelastic collision), the law of conservation of momentum applies. The total momentum before the collision is equal to the total momentum after the collision. And the total momentum of the system is the sum of the momenta of the individual objects.
• Analysis of options:
• Option A: According to the law of conservation of momentum, when two cars collide and stick together, their momenta are added together (vectorially, but in the case of one - dimensional motion, just arithmetically) to get the total momentum of the combined system. This is correct.
• Option B: Momentum is conserved in a collision (assuming no external forces), so it is not lost. So this option is wrong.
• Option C: There is no reason for the momentum to be reduced to zero unless the initial momenta were equal in magnitude and opposite in direction, but the question just says two cars collide and stick together, not anything about their initial velocities. So this option is wrong.
• Option D: Momentum is conserved, so it is not increased. The total momentum remains the same as the sum of the initial momenta. So this option is wrong.
• Answer for 48: A. Added together

Question 49

• Concept: The formula for momentum is $p = mv$, where $p$ is momentum, $m$ is mass, and $v$ is velocity (which has both speed and direction).
• Analysis of options:
• Option A: Mass is a part of the momentum formula ($p = mv$), so mass affects momentum. This option is wrong.
• Option B: Speed is the magnitude of velocity, and since $p = mv$, speed (as part of velocity) affects momentum. This option is wrong.
• Option C: Temperature is a measure of the average kinetic energy of the particles in a substance. It has no direct relation to the momentum of an object (which depends on mass and velocity). So temperature does not affect momentum. This option is correct.
• Option D: Direction is part of velocity, and since momentum is a vector quantity, the direction (which affects the sign of velocity in one - dimensional cases) affects momentum. This option is wrong.
• Answer for 49: C. Temperature

Question 50

• Concept: From the momentum formula $p=mv$, if the mass $m$ remains the same and the speed (magnitude of velocity) $v$ doubles, we can find the new momentum $p'$. Let the initial speed be $v_1$ and the final speed be $v_2 = 2v_1$, and the mass be $m$. The initial momentum $p_1=mv_1$, and the final momentum $p_2 = m\times v_2=m\times(2v_1) = 2mv_1 = 2p_1$.
• Analysis of options:
• Option A: Since the speed doubles and mass is constant, the momentum will not stay the same. This option is wrong.
• Option B: As we saw from the formula, if speed doubles (and mass is constant), the momentum doubles. This option is correct.
• Option C: The momentum will not triple because the speed only doubles. This option is wrong.
• Option D: There is no reason for the momentum to drop to zero. The mass is constant and the speed is increasing, so momentum should increase. This option is wrong.
• Answer for 50: B. Double

For the other questions, since the text is a bit unclear, but assuming they are also physics - related (due to the momentum - related questions), we can analyze them in a similar way. However, with the given clarity, we have solved the last three questions. If you can provide a clearer image or text for the other questions, we can solve them too.